did. Anyway, we may be reasonably certain that when Granett left you

with the dying or dead man, he ran off to Ambrose's flat--a few minutes away."

"Why didn't he come back?" demanded Hetherwick. "I'm only wanting to get at probabilities."

"I've thought of that, too," replied Mapperley. "I think he found Ambrose out. But by that time he'd had time to reflect. He knew something was wrong. He knew that if he went back, he'd find the police there, and would be questioned. He might be suspected. And so--he went home, with the bottle in which Ambrose had given him a drop of whisky for himself. And--died in his sleep, as they thought Hannaford would."

"Why should Ambrose have that bottle down at Westminster?" asked Hetherwick.

"Why shouldn't he?" retorted Mapperley. "A man who's taking a tonic takes it at least three times a day--regularly. He'd have his bottle with him. Probably there are several similar empty bottles there at that place."

"Where is that place?" exclaimed Hetherwick. "Where?"

"Got to be found," said Mapperley, as the cab came to a stand. "But--here's this!"

Hetherwick led his companion across Paddington Green and to the house from which he and Matherfield had watched the flats opposite. Late as it was, the lodging-house keeper was up, and lent a willing ear to Hetherwick's request that he should go with him to his friend the caretaker of the Mansions. That functionary was at supper. He continued to sup as Hetherwick, morally supported by the lodging-house man, explained matters to him, but at last he allowed his cheek to bulge with unswallowed food and turned a surprised and knowing eye on his principal visitor.

"Blamed if I didn't wonder whether it was all O.K. with that chap!" he exclaimed, banging the table with the haft of his knife. "For all he was quite the gentleman, I somehow suspicioned him! And yet, he'd a straight tale to tell: come here on Madame's behalf, to get something for her out of her rooms, had her keys, and give me a note from her saying as how I was to allow the bearer to go up to her flat! What more could I expect--and what could I do--under the circs? I asks yer!"

"Oh, he had a note, had he?" inquired Hetherwick. "In Madame's writing?"

The caretaker laid down his knife, and thrusting his hand in his breast-pocket, drew forth an envelope and silently handed it over. It was an azure-tinted envelope, of a very good quality of paper, such as is only sold in high-class stationery shops, and the sheet inside matched it in tint and quality. But Hetherwick at once noticed something about that sheet; so, too, did Mapperley, peering at it from behind his elbow. About an inch and a half had been rather roughly cut off at the top; obviously some address had been engraved, or embossed, or printed on the missing portion. As for what was written on the sheet, it was little--a simple order that the caretaker should allow bearer to go into Madame Listorelle's flat.

"You recognised that as Madame's handwriting?" suggested Hetherwick.

"Oh, that's her fist, right enough, that is!" replied the caretaker. "I knew it at once. And no wonder! I ain't no scholard, not me!--but I knows enough to know that it 'ud puzzle one o' them here forgers as ye reads about to imitate that there sort o' writing--more like as if it had been done with a wooden skewer than a Christian pen! Oh, that's hers."

Hetherwick handed the letter and envelope to Mapperley, who was holding out a hand.

"Well," he said. "I wish ye'd just let me have a look into Madame's flat. There's something seriously wrong, and----"

"Oh, you can do that--'long as I'm with you," said the caretaker readily. He rose and led the way to the left, and presently ushered them into a smart flat and turned on the electric light. "Don't see nothing wrong here," he observed. "The chap wasn't here ten minutes, and he carried nothing heavy away, whatever he had in his pockets."

Hetherwick and Mapperley looked round. Everything seemed correct and in order--the surroundings were those of a refined and artistic woman, obviously one who loved order and system. But on a desk that stood in the centre of the sitting-room a drawer had been pulled open, and in front of it lay scattered a few sheets of Madame Listorelle's private notepaper, with her engraved address and crest. Near by lay some envelopes, similarly marked. And with a sudden idea in his mind, Hetherwick picked up a sheet or two of the paper and a couple of envelopes and put them in his pocket.

A few minutes later, once more in the cab which they had kept waiting, and on the way to Hill Street, whither Hetherwick had bidden the driver go next, Mapperley turned to his employer with a sly laugh, and held up something in the light of a street lamp by which they were passing.

"What's that?" asked Hetherwick.

"The order written by Madame Listorelle," answered Mapperley, chuckling. "The caretaker didn't notice that I carried it off, envelope and all, under his very eyes! But I did--and here it is!"

"What do you want to do with it?" demanded Hetherwick. "What's your notion?"

But Mapperley only chuckled again and without giving any answer restored the azure-tinted envelope and its contents to his pocket.