it was now two o'clock. greg said to estuban,

"come to the corner drug-store with me. i am to receive a report there from the man who is watching de socotra. he may give us something to go on."

this was the substance of pa simmons' communication:

"an hour ago i took up my place where i could watch the entrance to the stickney arms. his nobs, the spanish gent, come out about one-thirty; there was a taxi waiting for him. he was carried down-town, me following, to a house on east seventeenth street near stuyvesant square, number 716 it was. he let his cab go and went in there. i drove around the corner, and letting my cab stand there come back and went into a lunch counter that was almost directly across the street, and where i could watch the house. i got my lunch while i waited. he was inside about half an hour. he come out with another fellow. his nobs had a little book in his hand."

"what kind of book?" asked greg eagerly.

"a sort of fat note-book, sort of narrowish and thick, with a black cover. it had different colored papers bound up inside it. he was turning over the pages as he come down the steps as if it had just been handed to him inside. so i saw it plain."

"what kind of man was with him?"

"another dago, fattish, clean-shaven, elegant dressed, a man with a sleepy kind of look."

"abanez," thought greg.

"well, the two of them started west on seventeenth, and i hustled back and got my cab and followed. 'tain't no cinch, though, to follow two men on foot when you're in a cab. i ran circles round the block so's they wouldn't catch on that i was trailing them. at the avenue they hailed a bus and rode up on top where i could watch them good. they went into a railway ticket office at thirtieth street. i followed them in. i saw soak-oater buy a ticket to washington and a parlor-car seat on the six o'clock train this evening. i heard him say to the guy with him: 'yew-neth,' or some such name says he, 'yew-neth will telegraph me during the afternoon what time the president will see me to-morrow.'

"well, the two guys parted outside the ticket-office, and soak-oater led me to a little hotel on irving place called—well, i can't say it because it's spanish, but you know the place. he's in there now, and i'm phoning from across the street."

greg's instructions to pa simmons were to stick to his man and report again in an hour, or as soon thereafter as he was able.

greg repeated the matter of his report to estuban.

"going to washington to see the president!" cried he, perplexed.

"who is yew-neth?" asked greg.

"evidently intended for nunez, the managuayan minister at washington, and one of de socotra's creatures of course." estuban was in a study.

"what do you make of it?" asked greg.

"i believe i'm beginning to see what he's up to," estuban replied slowly. "it's a devilish scheme, worthy of de socotra!"

"you mean he's going to impersonate bareda when he sees the president?"

"exactly! not content with murdering my poor friend he intends to blacken his memory. nunez will introduce him as antonio bareda. the visit will be reported in the newspapers—bareda sees the president, and the news will be cabled to managuay. what de socotra will tell the president one can guess; it will certainly not be anything that will lead him to take action in managuay. perhaps that will be reported in the papers too: 'bareda tells the president managuay is happy and contented under the present regime!' in any case when bareda fails to return to managuay his poor followers, who are so anxiously hanging on the result of this visit, will believe that their champion has betrayed them. how simple!"

"how devilish!" added greg.

estuban said: "de socotra must be arrested before he gets on the train."

greg thought anxiously of amy. "that won't do you any good," he said quickly. "you couldn't prove in advance that he intended to impersonate another."

"i could prove the murder."

"not without se?orita de socotra. and she won't testify against him."

"then must he go free?" cried estuban stormily.

"no. let us get the little black book from him and he is helpless. you could carry that to the president yourself."

"how do you purpose getting hold of it?"

"i don't know yet. i have four hours before train time. i'll find a way. at least i know now that it is on his person."

"go ahead and see what you can do. but if you fail i must hold myself free to act. i will be on the train on which he travels to washington."

"but he must know you," said greg.

"i shall be disguised."

this gave greg an idea. "do you know anything about disguises?" he asked eagerly.

"oh, yes," said estuban smiling grimly. "that's a very necessary part of a conspirator's work in managuay."

"could you disguise me?"

"what as?"

"a shabby old cabman."

"that oughtn't to be hard with the examples we have before us down here."

"good! i have to meet a man up-town at two forty-five. you get together what materials you need, and i'll be back at the yard in an hour."

hickey was taking the de socotra ladies to a matinee this afternoon. after he had dropped the ladies at the theater greg met him by appointment at the nearest corner. after his unhappy parting with amy the night before greg did not know what to expect. there was a note for him in the usual place. he devoured it. it was sufficiently baffling. the tone was friendly, but there was not the slightest reference to the ride home the night before. on the whole greg was relieved.

"what did you do to poor henry? he came back from his visit to you in a fit of the black sulks and has been lecturing me ever since. men are so trying! i'm sorry i had no luck with the l.b.b. i anxiously await word from you. francisco says he is going out of town this afternoon, but gives us no hint of his destination. he says he'll be back day after to-morrow, and then we'll all go home. i am distracted with anxiety and completely at sea.

"have you any news?

"amy w."

"what's orders for the afternoon?" asked hickey. "shall i try to pick up a little trade until 4.45?"

greg was standing with a hand on the cab, lost to his surroundings. his plan was beginning to take shape. he shook his head. "no time for that. hickey," he said suddenly, "can you drive pa simmons' car, the pack-arrow?"

"sure!"

"good! then i'll want you to change with him. you can tell the ladies when you come back that your own car broke down, see? i'll take the flivver because i know its ways."

first greg had hickey take him to a firm of stationers, where after a somewhat lengthy search through the stock he found a loose-leaf note-book bound in black seal that at least in a general way resembled the famous little black book. this greg carried to the stickney arms where he delivered it to his friend the hall-boy with a dollar and instructions to slip it to he knew who. as the boy was beginning to look on this affair as a regular source of income, there was little danger that he would fail him.

greg, hickey and the flivver then hastened down to the yard.

pa simmons called greg up soon after and reported that de socotra was now at the office of the managuayan consulate on thirty-sixth street.

"has he his bag with him?" asked greg.

"no."

"good! then he'll have to go back to the hotel for it. we have a line on him now. you needn't wait. come on down to the yard. i want to borrow your cab for awhile."

in his room greg wrote to amy:

"important developments. dare not trust them to paper. we have found a friend. it is to washington that f. goes this afternoon. he hopes to see the president to-morrow. i have learned that he is now carrying the l.b.b. on his person, and i'm going to put it up to you to get it. here is my plan. i will send him this telegram timed to reach him just before he leaves his hotel for the train: 'must see you for a few minutes before you leave town. come to the apartment. amy.' i am depending on you to find an excuse for telegraphing him, and to secure what we are after if you are able. you will need a similar book as a substitute, and i have sent you one through the hall boy, frank. perhaps i am asking the impossible, but it was the best plan i could think of. i was handicapped by not being able to talk things over with you. anyhow, i know you'll do your best. if you fail, don't lose heart, for i'll be there to have a try, and after me there is a third in reserve. frank has told me that your apartment is on the eighth or next to the top floor, and that the window of your own room is the third from the corner on the river side. i shall be watching that window while f. is with you. if you get the l.b.b. from him hang something white out of that window, and i'll know everything is all right. if i have luck f. will be riding in my cab, but in any case i'll be hard on his trail.

"greg."

when pa simmons came in with his cab this note was slipped in the usual place behind the back seat, and hickey was dispatched up-town in the pack-arrow to take the ladies home from the theater. pa simmons enjoyed a well-earned rest.

meanwhile in the little hall-room, mario estuban was practicing the art of disguise on greg. to begin with they borrowed the outer wear of pa simmons entire. under ordinary circumstances this would have been disguise enough, but as greg had been somewhat similarly attired on the night he first drove de socotra around town, they had to go further. estuban knew better than to attempt the impossible; he could not have made an old man out of the smooth-faced greg; at least not one that would have stood scrutiny under the light of day. but with a touch of paint he made his eyes red-rimmed and bleary, and put on a pair of cheap spectacles. a clay-colored pigment rubbed into his cheeks made them look hollow and unwholesome; a ragged mustache, and a lank lock of hair sticking down from under the peak of his cap completed the picture. as a last touch of realism, in the yard below greg grimed his hands and blackened his nails. his own mother would not have recognized him.

"holy smoke!" cried pa simmons; "looks like he was born in an owl taxi and never seen the light of the sun since!"

meanwhile pa simmons had been looking over the flivver, giving her a little grease here and there, and tightening up a nut or two. with blossom's help he succeeded in modifying the list to starboard that was her most characteristic peculiarity. in case de socotra might have remarked her license number on a previous occasion they changed plates for to-night with blossom's car.

greg took the wheel, and blossom cranked her. bessie waved good-by from the kitchen doorway. all knew that a crisis in the affairs of greg and amy was due this night. after the customary fusillade of backfires while she was warming up the flivver moved out of the yard.

it was now shortly after four. greg hastened up-town and from the telegraph office nearest the stickney arms sent his decoy telegram to de socotra. returning then to irving place he took up his stand just above the hotel dos estados unidos where he could watch the entrance. to all those who offered to engage him he shook his head and pointed to the flag on his taxi-meter which was down.

his principal fear was that the telegram might be delivered too soon, and de socotra get to the apartment before the ladies returned from the theater. this would be a calamity since amy would be unprepared for him; she could not be expected to get a chance to read greg's letter until she got home.

but as five o'clock approached and there was no sign of de socotra, greg's anxieties took another direction. suppose the telegram were not delivered until after de socotra had left for the station; suppose he had already been to the hotel for his bag, and would not get the telegram at all.

choosing a moment when the little lobby was well-filled greg inconspicuously made his way in and helped himself to a drink from the water-cooler. as he passed the desk he glanced in box 318. the key was not there; de socotra then was presumably in his room. so far so good. greg returned to his cab with an easier mind.

at five minutes past five a messenger boy entered the hotel with several telegrams, among which greg devoutly hoped might be the one he had sent. at ten minutes past five de socotra issued out of the hotel. in one hand he carried his valise, in the other an opened telegram. his face bore an expression of strong annoyance not unmixed with alarm.

greg eagerly called his cab to his attention. "taxi, sir?"

de socotra came quickly towards him, and greg stooping cranked his car. thus de socotra got in without obtaining a good look at his chauffeur. in a few minutes it would be dark. greg slid into his seat, and turned an ear towards the back of his car.

"where to, sir?"

"stickney arms apartment house, riverside and ninety-fourth. and hurry. double fare if you get me there and back to the southern terminal before six."

touching his cap, greg opened her up. deep within him he chuckled with satisfaction; de socotra obviously had no suspicion that he had ever engaged that cab before.

as de socotra got out at the stickney arms he said with scarcely a glance at greg: "let your engine run. i shan't be in here more than five minutes."

greg waited in what anxiety can be imagined. the five minutes seemed like as many hours. from where he stood beside his cab he could not see the windows of the eighth floor, so he backed across the road and looked up. on this part of riverside the houses are not built directly on the drive, but on a narrow roadway terraced above it. there were ornamental bushes and shrubs on this slope. it was almost dark now and many of the windows showed lights, but not the third window from the corner on the eighth floor.

greg tried to picture to himself what was going on within the apartment. all of a sudden his plan seemed preposterous to him. how could he expect the carefully-reared amy suddenly to play the part of a pick-pocket successfully!—and in five minutes. if she tried it at all he feared it would only be to betray herself to de socotra with perhaps tragic results.

but just as he had made up his mind to the worst his heart gave a great leap of gladness, for from the window he watched fluttered something white. she had actually done it! bravo, amy!

he returned to his cab. presently de socotra reappeared, and at the same moment henry saunders came around the corner on foot. the two men met at the foot of the steps. they addressed each other in spanish, but from expression and gesture it was not difficult to guess what was said. saunders told de socotra that he had something important to tell him. de socotra replied that he was in a hurry to catch his train and invited saunders to ride down-town with him. the two men entered the cab.

greg's face turned grim. what was the nature of saunders' communication? was it possible that amy's fiancé intended to betray them?

de socotra said: "back to the southern terminal. you can make it if you hurry. you have twenty-five minutes."

turning into the drive proper, greg speeded downtown. on that broad thoroughfare, unimpeded by cross traffic, the speed limit is a little bit eased. at the end of the drive he bore through seventy-second street, but instead of continuing down-town by broadway, the main motor highway, he turned into amsterdam, and running in the car-tracks of that unfrequented street opened her up wide.

he would have given much to hear what was being said behind. whatever it was he fervently hoped that it would not prevent de socotra from taking his train. once he saw him safe aboard that train greg determined that he would go openly to amy and get the little black book from her. once they had that precious evidence in their hands, little matter if de socotra did discover their relations. but amy could scarcely go on living under his roof.

greg had reached the boundary of the western central freight yards and had turned east to find a better street down-town when he was startled by a violent rapping on the glass behind him. at the same moment de socotra opened the cab door.

"go back! go back!" he cried in a strained, harsh voice. "back to the apartment!"

as he turned around in the street, greg stole a glance into the back of the cab. he could not see the face of either man, but revealed by the light of a street lamp he saw the little black book open in de socotra's hands. so the worst had happened. saunders had betrayed them, and de socotra had discovered the substitution. greg's heart contracted sharply. how could he warn amy in time?

he turned back into amsterdam avenue, and headed north again. in his efforts to collect his thoughts he instinctively slowed down. de socotra hammered on the glass and yelled:

"faster! faster! what's the matter with you?"

presently he changed his mind. opening the door again he said: "stop at that drug-store yonder, i want to telephone."

the two men tumbled out of the cab. they were disputing excitedly in spanish. saunders seemed to be making some kind of appeal, which de socotra furiously denied. the latter's face was livid and distorted with rage. gone was the smiling courteous veneer. greg was appalled at the revelation of the man's true character. on the other hand saunders seemed almost ready to weep.

"he is scared now at what he started," thought greg grimly.

de socotra, waving saunders away, went into the drug-store. saunders, holding his hands above his head and talking to himself, walked blindly away down the side street.

"he hasn't even got wit enough to warn her what is coming," thought greg. "i must do it."

through the lighted windows of the drug-store greg saw that the telephone booth that de socotra entered adjoined the soda-water counter. obeying a sudden impulse he followed him into the store.

the soda-clerk grinned at greg and cocked a humorous eyebrow in the direction of the telephone booth. "bug-house, i guess?"

greg shrugged and grinned in kind, and ordered a lemon phosphate. while it was being drawn he edged along the counter towards the booth. through the glass he saw that de socotra had his back towards the door—for that matter greg didn't much care now if he did begin to suspect him.

many of these supposedly sound-proof booths are flimsy affairs, and greg, straining his ears, was able to hear a good deal of what de socotra was saying. the soda-clerk, taking in the situation, continued to grin appreciatively.

de socotra got the number he asked for and started talking. the first thing greg heard distinctly was: "yes, treachery in my own household! but i'll take care of that."

later greg heard him say: "i called you up because you know this town. i want the address of a private madhouse—well, sanitarium if you like it better. at once. to-night. a high-class place, expensive and all that. well, please find out for me and let me know quickly at my apartment. and get abanez on the wire if you can, and tell him to come to me."

greg gasped inwardly. the man's boldness staggered him. no need to ask who the madhouse was for! before he could collect his wits de socotra was out of the booth. greg hastily put his glass to his lips.

"damn you, have you nothing better to do than drink slops!" cried de socotra furiously. "come on!"

this was nuts to the soda-clerk. he came to the door to see the last of this diverting pair.

by the time they started, greg had made up his mind what to do. a few blocks farther up the street—they were in the forties now—he saw a garage and pulled up at the door.

de socotra with a violent oath demanded to know what he was stopping for.

"out of gas," said greg laconically.

de socotra swore and stamped on the pavement like a man beside himself. greg stared at him, affecting a stupid wonder. a trolley car came up the avenue. de socotra tossed greg a bill without looking at it and running out in the street swung himself aboard the car.

for an agonized instant of indecision greg debated whether he would do better to jump back in his cab, and endeavor to beat de socotra to the stickney arms, or stop and telephone. but the car was traveling fast, and de socotra could surely get another cab at the broadway intersection. greg ran into the garage to telephone.

ages seemed to pass while he was getting the apartment house. he ground his teeth and prayed for patience. as a matter of fact there was no undue delay. he asked for se?orita de socotra, and there was another fifteen seconds of agony before a feminine voice answered on the wire—not the crisp tones of amy, alas! but the languorous bianca. greg cursed himself for his folly in supposing that they would allow amy to answer the 'phone.

"i want to speak to se?orita de socotra," he said.

"who are you?" asked bianca.

in an evil moment greg answered "abanez." in his excitement he forgot that bianca and abanez were cronies. a flood of spanish answered him. he could only say lamely:

"yes, i know, but i wanted to speak to amèlie."

"i don't know of whom you are speaking," the voice said in cold hard english. "you have the wrong number," and click! the connection was cut.

by violently agitating the receiver greg succeeded in getting the operator at the stickney arms. he asked for frank, the hall-boy. this was what he ought to have done in the beginning. he had only wasted a precious two minutes, and put bianca on her guard.

"this you, frank? this is the fellow who passes you notes for the little spanish lady, do you get me? i gave you a little package this afternoon."

"sure, i know you, boss."

"listen; go quick to her apartment—don't telephone. tell her her father is coming back and to beat it, see? tell her the old cab will be at the door in five minutes. i'll make it all right with you."

"i get you, boss."

"be quick! he's almost there!"

greg then drove the flivver for all there was in her to sherman square, to riverside, to ninety-fourth street. as he ran up the narrow roadway to the stickney arms a cab stopped there ahead of them. de socotra sprang out and ran up the steps. the cab went on.

greg stopped just beyond the steps, and waited for a moment or two. if amy had got out safely, she would be on the lookout for him. but she did not appear. his anxiety became insupportable. he could not rest. he went into the apartment house to learn what had happened. the gorgeous blue-clad ones looked askance at the shabby driver. the boy he knew was not in sight.

"where is frank?" he asked.

"up-stairs."

even as he asked frank stepped out of an elevator. there were two elevators, and evidently de socotra had gone up in one as frank came down in the other. greg beckoned frank aside from the others.

"i'm the fellow that telephoned you just now—about miss de socotra."

frank's jaw dropped.

greg had not time to make explanations. he showed the boy the five dollar bill de socotra had just tossed him. that did the trick, though the boy still gaped at him.

"you gave her my message?"

"yes, just now."

"only just now! it was a good five minutes ago!"

"i know. it wasn't my fault. they kept me waiting at the door. i suppose the girl had to wait for a chance to slip her word."

"you should have told the maid! she's safe."

"how was i to know that?"

"is she out of the place?"

"no, she went back for something."

greg groaned. "then it's too late. he's just gone up."

the boy whistled.

greg jumped for the elevator. but the boy hung back. greg was too disreputable looking for the stickney arms. during that pause from somewhere far up in the building the sound of a slammed door came down the stair well.

"take me up!" cried greg. "how do you run this damned thing!"

a signal showed on the telephone switchboard. "his number!" said one of the boys springing to answer, and greg paused.

"yes, sir, all right, sir," stammered the boy at the board.

he jumped up breathless with excitement. "the spanish gent! he says the girl's run out. he says she's not herself. he says stop her. and one of us go up and bring him down."

the elevator signal was already ringing continuously. greg stepped out. he cast a significant glance around from boy to boy.

"my cab's just beyond the door. a fiver to each of you fellows if she gets in it safe!"

he ran outside and waited for her in his cab, the door standing open, his foot ready to let in the clutch the moment she jumped in. but the seconds passed and she did not appear. looking anxiously out and back he saw de socotra come to the door of the apartment house with the four boys at his heels. he heard him say:

"i tell you, she came down-stairs."

"she didn't pass this way, sir."

from the head of the steps they looked uncertainly up and down the street, and then went back into the building. greg had drawn back out of sight. a moment later another cab drew up behind greg, and two men got out. it was the puffy abanez and another of the gang. at the same instant amy, bareheaded, came running like a deer around the corner out of ninety-fourth street. the two men stared, rooted to the pavement in astonishment. amy ran on to greg's cab, but at the sight of the strange face, she drew back.

"it's all right," he whispered swiftly. "it is i, greg."

she climbed in, he slammed the door, and they were off. de socotra came running out of the building again. he met the two men on the sidewalk. all three jumped in the waiting cab and came on.