on returning to the silbury hotel. gerald sat down to think over the important conversation with rebb. to all appearances the master was as innocent as the man. nevertheless, according to the major, geary had been to the pixy's house on the fatal night, in spite of his denial. on the face of it, the negro had no reason to kill bellaria, and rebb had sworn that the murder was neither committed nor prompted by him. if this were so, it appeared strange that rebb should have found geary, not only in the grounds of the pixy's house, but in the mansion itself, when he arrived. seeing that geary was thus first in the field, it was not improbable that he had caught a glimpse of the assassin. whether he had, and had told his master, it was of course impossible to say. but haskins determined to have another interview with the landlord of the devon maid, and force him to disclose the whole truth, which he assuredly had not told in his wife's presence.

one important thing gerald had learned from rebb, and that was the truth of his surmise regarding charity. she was--as he had always supposed--the twin sister of mavis, and haskins congratulated himself on guessing this before rebb had spoken out. still, it was just as well that rage had made the major thus candid, and the matter was put beyond all doubt. haskins was pleased also by the discovery, as, guided by him, mavis would be quite willing to divide the income, and then lady euphemia would not be angry at tod's runaway marriage. so far everything was right.

but the mystery of the crime had still to be solved. until it was, mavis must continue, not only to be an outcast and a fugitive from justice, but must remain unable to claim her rights as julian durham's heiress. apparently geary and rebb and signor venosta, as an emissary of the tána society, were all innocent. if so, who was the guilty person? gerald wondered, if the letter to which mavis had referred could be found, as he firmly believed that it would afford a clue to the identity of the criminal. in his own mind he constructed the manner in which the crime had been committed. bellaria had received this mysterious letter, which for some reason overcame her fears sufficiently to make her venture out at night. to meet the writer of the letter she had opened the gates, and then had been stabbed by her own knife--geary's weapon--which had been wrested from her in a hand-to-hand struggle. the wonder was that the struggle had not attracted attention. as it was, rebb swore that he had heard only one scream, and that might have been uttered by mavis when she found the dead body of the nurse. bellaria therefore was in all probability slain unawares.

however, it was useless to build up theories, which were all moonshine, so gerald resolved to wait until tod and arnold arrived. according to macandrew's letter, they would come to silbury early the next day, so gerald had a good many hours to himself. he had half a mind to see inspector morgan, and learn all details concerning the inquest, as some possible evidence might have been obtained, likely to throw light on the darkness. but haskins refrained from doing so, as he did not wish to arouse morgan's suspicions and reopen the case. for mavis' sake the quieter he moved in the matter the better it would be. gerald wondered, after hearing rebb's acknowledgment of charity's birth, if he had any idea of the scheme by which the girls had been made to change places. but, after reflection, he decided that it was impossible, as mrs. pelham odin had managed very cleverly. also rebb was unaware that the twin he had got rid of was now mrs. macandrew, and, since that young lady was at amsterdam, there would be no chance of her being met by mrs. berch and her daughter, when in switzerland.

bearing in mind what mrs. crosbie had told him of her projected tour abroad, gerald was greatly surprised when he met the widow and her mother driving up the silbury high street from the railway station.

she saw him at once, as he stood thunderstruck on the pavement, and beckoned for him to come to the side of the landau.

"you are surprised to see us here," she said, with a gay smile. "this is not switzerland, is it?"

"you said nothing about coming down here yesterday," he answered.

"no, because neither i nor my mother had any intention of coming. it was this way, gerald. michael--major rebb, you know--came in almost as soon as you had left, and we told him all that had taken place."

"why did you do that?" asked haskins imperatively.

"don't bully, gerald," said mrs. crosbie tartly. "i told michael because i have no secrets from michael, and he was very angry that you should have spoken to me as you did."

"i was perfectly polite, permit me to remind you, madge."

"don't call me by my christian name," she said as usual, "well then, michael went away to have an explanation with you, and later telegraphed to me that you had gone to devonshire and that he intended to follow at once. he also asked us to come down that we might see the pixy's house, as we intend to repair it when we marry."

"do you indeed?" muttered haskins ironically.

"of course," said mrs. crosbie, with an airy flutter of her laces, "and i may tell you, gerald, that i came down the more willingly, since i do not want you and michael to quarrel. that is why we are here."

"to see the house, and to prevent a quarrel," said gerald coolly. "i am greatly obliged to you for the trouble you have taken, mrs. crosbie, but i have already seen the major."

mrs. berch, who had hitherto kept silence, looked up sharply. "have you had a quarrel?" she demanded eagerly.

"yes and no. rebb was slightly difficult to deal with, but we now understand one another."

mrs. crosbie asked: "what about?"

"about various things," answered haskins carelessly. he was determined not to answer her questions, as he had a vague idea that she was not so honestly his friend as she pretended to be.

"and you parted amiably, i hope?" said mrs. berch.

haskins laughed as he remembered the parting, and how he had locked rebb in the room. "i think that the major would gladly see me tarred and feathered," he said lightly.

"there!" cried mrs. crosbie, with a childish pout. "i knew you had quarreled, and i did so wish you to be friends. i want you to come to the pixy's house when i marry michael and see the improvements. i have already arranged what to do."

"have you been down here before then?" asked gerald, astonished.

"yes--over two years ago. michael asked me down when we were first engaged. i saw that poor bellaria, but not mavis."

"why did you not see mavis?"

"because michael said her mental state was so sad, that she might be dangerous. she was shut up on the day i went over the house, and, as i was only there for an hour, she knew nothing of my visit. i and mother were stopping in the neighborhood--it was when i was learning to drive a motor, gerald. i would have taken that poor girl out for drives, as i got to know the country so thoroughly, but it was too dangerous."

"where did you stop?" asked gerald, still lingering, although mrs. berch seemed inclined to cut short her daughter's chatter.

"at a village miles away, called belldown. why do you start?"

"a mosquito stung me," answered haskins readily: but his real reason for starting was that belldown happened to be the place where mr. arnold and tod were now stationed. "there are heaps of mosquitoes here, mrs. crosbie. you will be stung."

"ah, well, we are only here for a couple of days--at the pixy's house, that is. i merely want to look round, and now that the poor mad girl has gone i can explore at my leisure. good-day. i wish i could ask you to come over, but michael might object. so stupid of you to quarrel with my future husband, when we are such friends."

she gave the signal to the driver of the landau to move on, and both she and her mother bestowed friendly smiles on the young man, as he took off his hat. gerald watched the carriage climb up the long street and vanish over the crest of the hill. then he walked back again to the hotel, wondering why mrs. crosbie was so anxious to retain his friendship when she became mrs. rebb. he knew that madge was a flighty woman, although much cleverer than she pretended to be, and was sure that she had some reason for all this friendliness and chatter.

however, he had more important things to think about than mrs. crosbie's airs and graces, and spent a wakeful night building up theories and knocking them down again. by dawn he had arrived at the conclusion that geary was the criminal. "i expect," thought haskins, while taking his bath, "that geary found his hold over rebb was getting lax, so he deliberately killed bellaria, knowing that the major had gone to the pixy's house, in the hope of getting blackmail by threatening to throw the blame of the murder on his master. and by the murder he secured to rebb an income out of which large sums could be paid. yes. i really believe that geary will prove to be the guilty person. but how am i to fix the crime on him?"

this was a hard question to answer, and gerald waited for the arrival of tod to put it to him, since two heads are better than one. the solicitor arrived at midday, along with arnold, having come from belldown--so they explained--by railway. tod looked anxious, and not so healthy as he had done in london, but haskins put this down to the man's unavoidable fretting after his bride. arnold had not changed in the least, and appeared to be as tiny and gnome-like as ever. first and foremost the two men, being hungry, had dinner, and then gerald conducted them both to the hotel drawing-room--a gorgeous apartment, which had been placed at his disposal by mrs. jennings, for an extra pound on the bill. having the apartment to themselves, the three men saw that the door was closed, and then sat down to talk. gerald immediately asked the question which had been trembling on his tongue from the moment he set eyes on his friend.

"in the first place, tod," he said impatiently, "what took you and arnold to belldown?"

"that is a long story," said tod leisurely.

"then tell it as shortly as you can."

"one moment, let us do things in order. first let me know your doings here, jerry."

"but----" began haskins with irritation.

tod cut him short. "see here, jerry," said he firmly. "i am supposed to be your solicitor, and it is my place to conduct the business. i want things done in order. first your story and then mine. both will be extremely interesting, i have no doubt."

gerald stared. "why should you think that i have anything to tell?"

"well," observed macandrew jocularly, "a little bird--mrs. jennings by name--whispered to me that two london ladies had come down on a visit to major rebb, who is camping--so to speak--at the pixy's house."

"yes. mrs. crosbie and her mother. what of that?"

"i shall tell you when i have heard what you have to say about them."

arnold uttered a grunt and raked his long beard with lean fingers. haskins looked from one to the other quite mystified. "has what you have to say anything to do with those ladies?"

"a great deal to do with them, jerry."

a light broke in on haskins' clouded brain. "mrs. crosbie said that she had stopped at belldown--that is where you have been."

"hum," said tod, glancing at arnold. "i didn't think she would have admitted so much."

"tod," gerald caught his friend's arm, "don't worry me with your hints and looks. has mrs. crosbie anything to do with this crime?"

"i can't say," rejoined the solicitor stolidly, "and i shan't speak until you tell me how you got along with rebb."

haskins threw himself back in his chair and made the best of a scotsman's obstinacy. "i have something very important indeed to tell you," he said seriously. "you know the likeness between the girls?"

macandrew nodded. "i told mr. arnold here all about it, and about your idea of the two beings twins."

"my idea has proved to be correct. they are twins."

tod jumped up, scattering his papers, and with his red hair almost standing on end. "do you mean to say that rebb----"

"yes. sit down. toddy, and listen," said gerald vigorously, and when his legal adviser became quiet he related the whole of the conversation with rebb.

"well i'm blessed," muttered tod, rubbing his head, when the narrative was ended, "what a wonderful thing! there is something in your intuitions after all, jerry."

"i don't think it needed much intuition to guess at a possible relationship, seeing how marvelously alike mavis is to charity. the wonderful part consists in my getting rebb to give himself away."

"ah," said arnold significantly, "the military gentleman is beginning to see that the wheel of fortune is turning the wrong way with him."

"and quite right too," said tod meditatively. "what a scoundrel the man is, to be sure! well, jerry, important as what you have told us is, i am more interested in the movements of mrs. crosbie and her mother. when you tell me about them i can explain what mr. arnold and myself have discovered at belldown."

"there is little to tell about them. rebb came down after me, and they came down after rebb. he asked his future bride here to have a second look at her future home."

"oh, so she had been here before?"

"yes--so she says--some time ago. this is her second visit."

"her third, more like," muttered arnold, in his beard.

"we can't be sure of that," said tod rapidly.

"for heaven's sake, tell me what you mean," cried haskins, jumping up in his turn, "my nerves are wearing thin with all this suspense."

"well then," began macandrew, shuffling with his papers, "it's this way. mr. arnold here was going about the country in his caravan, selling books, and reached belldown on the same day that mavis fled."

"mavis fled at night."

"well, well," cried macandrew testily, "you know what i mean. arnold was at belldown on the day of the night when mavis fled and the murder was committed. is that plain enough?"

"yes. go on, toddy. don't be a silly ass."

"i am your solicitor just now and not your pal," said tod, with great dignity; "well then, while wandering about belldown, arnold saw two ladies in a motor car. one was driving and one was being driven."

"and they were----"

"mrs. berch and her daughter, whom we, jerry, supposed to be at bognor. i never knew that mrs. crosbie could drive a motor."

"oh yes. i taught her a trifle myself, and she is quite an expert at the business. she mentioned to-day, when i stood by her carriage, how she had motored over every inch of the country. but what was she doing down hereabouts, when----"

"when she was supposed to be at bognor? that is what i want to ask her, and i am glad that she is on the spot."

gerald thought for a few moments. "how did you recognize these ladies, mr. arnold?"

"major rebb once showed me a colored photograph of the lady to whom he was engaged, and i recognized mrs. crosbie when she passed in her motor. a severe-looking old lady in black was with her, and mr. macandrew tells me that she is mrs. berch, the mother. i may tell you that the two ladies wore motor goggles and veils."

"then how did you recognize them?" asked gerald again.

"mrs. crosbie's veil was up as they passed, and she pulled it down when she saw that i was looking earnestly at her. the motor was going very slowly at the moment because a hay wain was in front blocking the road."

"i see. well, what happened?"

"the motor went to the inn at belldown. it was about six o'clock, and the two ladies had dinner. they were at the inn when i left belldown in my caravan on the way to leegarth where i hoped to rescue mavis."

"yes! yes! yes!" cried tod, impatient at the slow way in which arnold was speaking, "and late that night--about ten o'clock--he passed the motor on the road between belldown and leegarth. it had broken down, and mrs. crosbie was tinkering with the machine."

"i shouldn't think she could mend a broken motor, tod."

"oh, i don't expect anything very serious was the matter. probably her driving--she drives furiously, as a woman always does--had put the gear out of order. however, arnold passed them and camped some distance outside leegarth, so that the villagers, who knew his face, would not recognize him. then, some time after eleven, he saw the motor coming along, also skirting the village. the two women were in it, and he thought that they had lost their way. and then again he fancied that mrs. crosbie was going to the devon maid to see rebb. at all events the motor passed out of sight in the darkness. i may tell you that its lamps were not lighted, so mrs. crosbie ran the risk of police interference. rather foolish, i think, seeing she did not want to be seen."

"well! well," said gerald, after a pause, "and what does all this mean?"

"arnold," went on tod cautiously, "did not attach much importance to this motor car business, but when he told me i fancied that mrs. crosbie had to do with the murder."

"i don't see how----"

"i do. she didn't want to be recognized: she had no lamps, so that she could slip along easily, and--as we learned at belldown--she did not return through the village. if she did not come down to murder bellaria, why was she in this neighborhood, and why did she lie to you about bognor?"

"it's a mare's nest you have found, tod. mrs. crosbie has no motive to murder bellaria, and she certainly hasn't the nerve."

"i'll ask her myself," said tod, rising. "come on over to leegarth."