the scotland yard inspector was, indeed, waiting on the platform, and greeted us warmly.

"well, moosior poirot, this is good. thought you'd like to be let in on this. tip-top mystery, isn't it?"

i read this aright as showing japp to be completely puzzled and hoping to pick up a pointer from poirot.

japp had a car waiting, and we drove up in it to croftlands. it was a square, white house, quite unpretentious, and covered with creepers, including the starry yellow jasmine. japp looked up at it as we did.

"must have been balmy to go writing that, poor old cove," he remarked. "hallucinations, perhaps, and thought he was outside."

poirot was smiling at him.

"which was it, my good japp?" he asked; "accident or murder?"

the inspector seemed a little embarrassed by the question.

"well, if it weren't for that curry business, i'd be for accident every time. there's no sense in holding a live man's head in the fire—why, he'd scream the house down."

"ah!" said poirot in a low voice. "fool that i have been. triple imbecile! you are a cleverer man than i am, japp."

japp was rather taken aback by the compliment—poirot being usually given to exclusive self praise. he reddened and muttered something about there being a lot of doubt about that.

he led the way through the house to the room where the tragedy had occurred—mr. paynter's study. it was a wide, low room, with book-lined walls and big leather arm-chairs.

poirot looked across at once to the window which gave upon a gravelled terrace.

"the window, it was unlatched?" he asked.

"that's the whole point, of course. when the doctor left this room, he merely closed the door behind him. the next morning it was found locked. who locked it? mr. paynter? ah ling declares that the window was closed and bolted. dr. quentin, on the other hand, has an impression that it was closed, but not fastened, but he won't swear either way. if he could, it would make a great difference. if the man was murdered, some one entered the room either through the door or the window—if through the door, it was an inside job; if through the window, it might have been any one. first thing when they had broken the door down, they flung the window open, and the housemaid who did it thinks that it wasn't fastened, but she's a precious bad witness—will remember anything you ask her to!"

"what about the key?"

"there you are again. it was on the floor among the wreckage of the door. might have fallen from the keyhole, might have been dropped there by one of the people who entered, might have been slipped underneath the door from the outside."

"in fact everything is 'might have been'?"

"you've hit it, moosior poirot. that's just what it is."

poirot was looking round him, frowning unhappily.

"i cannot see light," he murmured. "just now—-yes, i got a gleam, but now all is darkness once more. i have not the clue—the motive."

"young gerald paynter had a pretty good motive," remarked japp grimly. "he's been wild enough in his time, i can tell you. and extravagant. you know what artists are, too—no morals at all."

poirot did not pay much attention to japp's sweeping strictures on the artistic temperament. instead he smiled knowingly.

"my good japp, is it possible that you throw the mud in my eyes? i know well enough that it is the chinaman you suspect. but you are so artful. you want me to help you—and yet you drag the red kipper across the trail."

japp burst out laughing.

"that's you all over, mr. poirot. yes, i'd bet on the chink, i'll admit it now. it stands to reason that it was he who doctored the curry, and if he'd try once in an evening to get his master out of the way, he'd try twice."

"i wonder if he would," said poirot softly.

"but it's the motive that beats me. some heathen revenge or other, i suppose."

"i wonder," said poirot again. "there has been no robbery? nothing has disappeared? no jewellery, or money, or papers?"

"no—that is, not exactly."

i pricked up my ears; so did poirot.

"there's been no robbery, i mean," explained japp. "but the old boy was writing a book of some sort. we only knew about it this morning when there was a letter from the publishers asking about the manuscript. it was just completed, it seems. young paynter and i have searched high and low, but can't find a trace of it—he must have hidden it away somewhere."

poirot's eyes were shining with the green light i knew so well.

"how was it called, this book?" he asked.

"the hidden hand in china, i think it was called."

"aha!" said poirot, with almost a gasp. then he said quickly, "let me see the chinaman, ah ling."

the chinaman was sent for and appeared, shuffling along, with his eyes cast down, and his pigtail swinging. his impassive face showed no trace of any kind of emotion.

"ah ling," said poirot, "are you sorry your master is dead?"

"i welly sorry. he good master."

"you know who kill him?"

"i not know. i tell pleeceman if i know."

the questions and answers went on. with the same impassive face, ah ling described how he had made the curry. the cook had had nothing to do with it, he declared, no hand had touched it but his own. i wondered if he saw where his admission was leading him. he stuck to it too, that the window to the garden was bolted that evening. if it was open in the morning, his master must have opened it himself. at last poirot dismissed him.

"that will do, ah ling." just as the chinaman had got to the door, poirot recalled him. "and you know nothing, you say, of the yellow jasmine?"

"no, what should i know?"

"nor yet of the sign that was written underneath it?"

poirot leant forward as he spoke, and quickly traced something on the dust of a little table. i was near enough to see it before he rubbed it out. a down stroke, a line at right angles, and then a second line down which completed a big 4. the effect on the chinaman was electrical. for one moment his face was a mask of terror. then, as suddenly, it was impassive again, and repeating his grave disclaimer, he withdrew.

japp departed in search of young paynter, and poirot and i were left alone together.

"the big four, hastings," cried poirot. "once again, the big four. paynter was a great traveller. in his book there was doubtless some vital information concerning the doings of number one, li chang yen, the head and brains of the big four."

"but who—how—"

"hush, here they come."

gerald paynter was an amiable, rather weak-looking young man. he had a soft brown beard, and a peculiar flowing tie. he answered poirot's questions readily enough.

"i dined out with some neighbours of ours, the wycherlys," he explained. "what time did i get home? oh, about eleven. i had a latch-key, you know. all the servants had gone to bed, and i naturally thought my uncle had done the same. as a matter of fact, i did think i caught sight of that soft-footed chinese beggar ah ling just whisking round the corner of the hall, but i fancy i was mistaken."

"when did you last see your uncle, mr. paynter? i mean before you came to live with him."

"oh! not since i was a kid of ten. he and his brother (my father) quarrelled, you know."

"but he found you again with very little trouble, did he not? in spite of all the years that had passed?"

"yes, it was quite a bit of luck my seeing the lawyer's advertisement."

poirot asked no more questions.

our next move was to visit dr. quentin. his story was substantially the same as he had told at the inquest, and he had little to add to it. he received us in his surgery, having just come to the end of his consulting patients. he seemed an intelligent man. a certain primness of manner went well with his pince-nez, but i fancied that he would be thoroughly modern in his methods.

"i wish i could remember about the window," he said frankly. "but it's dangerous to think back, one becomes quite positive about something that never existed. that's psychology, isn't it, m. poirot? you see, i've read all about your methods, and i may say i'm an enormous admirer of yours. no, i suppose it's pretty certain that the chinaman put the powdered opium in the curry, but he'll never admit it, and we shall never know why. but holding a man down in a fire—that's not in keeping with our chinese friend's character, it seems to me."

i commented on this last point to poirot as we walked down the main street of market handford.

"do you think he let a confederate in?" i asked. "by the way, i suppose japp can be trusted to keep an eye on him?" (the inspector had passed into the police station on some business or other.) "the emissaries of the big four are pretty spry."

"japp is keeping an eye on both of them," said poirot grimly. "they have been closely shadowed ever since the body was discovered."

"well, at any rate we know that gerald paynter had nothing to do with it."

"you always know so much more than i do, hastings, that it becomes quite fatiguing."

"you old fox," i laughed. "you never will commit yourself."

"to be honest, hastings, the case is now quite clear to me—all but the words, yellow jasmine—and i am coming to agree with you that they have no bearing on the crime. in a case of this kind, you have got to make up your mind who is lying. i have done that. and yet—"

he suddenly darted from my side and entered an adjacent bookshop. he emerged a few minutes later, hugging a parcel. then japp rejoined us, and we all sought quarters at the inn.

i slept late the next morning. when i descended to the sitting-room reserved for us, i found poirot already there, pacing up and down, his face contorted with agony.

"do not converse with me," he cried, waving an agitated hand. "not until i know that all is well—that the arrest is made. ah! but my psychology has been weak. hastings, if a man writes a dying message, it is because it is important. every one has said—'yellow jasmine? there is yellow jasmine growing up the house—it means nothing.'"

"well, what does it mean? just what it says. listen." he held up a little book he was holding.

"my friend, it struck me that it would be well to inquire into the subject. what exactly is yellow jasmine? this little book has told me. listen."

he read.

"'gelsemini radix. yellow jasmine. composition: alkaloids gelseminine c22h26n2o3, a potent poison acting like coniine; gelsemine c12h14no2, acting like strychnine; gelsemic acid, etc. gelsemium is a powerful depressant to the central nervous system. at a late stage in its action it paralyses the motor nerve endings, and in large doses causes giddiness and loss of muscular power. death is due to paralysis of the respiratory centre.'

"you see, hastings? at the beginning i had an inkling of the truth when japp made his remark about a live man being forced into the fire. i realised then that it was a dead man who was burned."

"but why? what was the point?"

"my friend, if you were to shoot a man, or stab a man after he were dead, or even knock him on the head, it would be apparent that the injuries were inflicted after death. but with his head charred to a cinder, no one is going to hunt about for obscure causes of death, and a man who has apparently just escaped being poisoned at dinner, is not likely to be poisoned just afterwards. who is lying, that is always the question? i decided to believe ah ling—"

"what!" i exclaimed.

"you are surprised, hastings? ah ling knew of the existence of the big four, that was evident—so evident that it was clear he knew nothing of their association with the crime until that moment. had he been the murderer, he would have been able to retain his impassive face perfectly. so i decided then, to believe ah ling, and i fixed my suspicions on gerald paynter. it seemed to me that number four would have found an impersonation of a long lost nephew very easy."

"what!" i cried. "number four?"

"no, hastings, not number four. as soon as i had read up the subject of yellow jasmine, i saw the truth. in fact, it leapt to the eye."

"as always," i said coldly, "it doesn't leap to mine."

"because you will not use your little gray cells. who had a chance to tamper with the curry?"

"ah ling. no one else."

"no one else? what about the doctor?"

"but that was afterwards."

"of course it was afterwards. there was no trace of powdered opium in the curry served to mr. paynter, but acting in obedience to the suspicions dr. quentin had aroused, the old man eats none of it, and preserves it to give to his medical attendant, whom he summons according to plan. dr. quentin arrives, takes charge of the curry, and gives mr. paynter an injection—of strychnine, he says, but really of yellow jasmine—a poisonous dose. when the drug begins to take effect, he departs, after unlatching the window. then, in the night, he returns by the window, finds the manuscript, and shoves mr. paynter into the fire. he does not heed the newspaper that drops to the floor and is covered by the old man's body. paynter knew what drug he had been given, and strove to accuse the big four of his murder. it is easy for quentin to mix powdered opium with the curry before handing it over to be analysed. he gives his version of the conversation with the old man, and mentions the strychnine injection casually, in case the mark of the hypodermic needle is noticed. suspicion at once is divided between accident and the guilt of ah ling owing to the poison in the curry."

"but dr. quentin cannot be number four?"

"i fancy he can. there is undoubtedly a real dr. quentin who is probably abroad somewhere. number four has simply masqueraded as him for a short time. the arrangements with dr. bolitho were all carried out by correspondence, the man who was to do locum originally having been taken ill at the last minute."

at that minute, japp burst in, very red in the face.

"you have got him?" cried poirot anxiously.

japp shook his head, very out of breath.

"bolitho came back from his holiday this morning—recalled by telegram. no one knows who sent it. the other man left last night. we'll catch him yet, though."

poirot shook his head quietly.

"i think not," he said, and absent-mindedly he drew a big 4 on the table with a fork.