Clo remembered Beverley's instructions, and went straight to her own room, but the threat of the ferret-man rang in her ears. "Tell your lady friend a life will pay for this. She's got till ten o'clock to-night, and not a minute more."

It was now after five, and Sister Lake was firmly bent upon undressing her charge. Clo had to let herself be tucked into bed. Meekly also she received the order to lie quite still and rest till dinner time.

Rest! As though she could rest, not knowing what ought to be done next to help the Angel! A passive plan occurred to Clo, which could do no harm, and her quick wit suggested how best to carry it out.

"I'll be as good as gold," she promised, "if you'll forgive me, Sister, and do me a favour. I feel sick because I spoilt your afternoon! You stayed in, waiting for me to come back, instead of taking your walk. Will you go out now, instead? I'll rest better if you will. Do, please!"

All Clo's Irish powers of persuasion were needed to coax Sister into consenting. Eventually she relented. Clo could have sung for joy as Sister Lake bade her "good-bye for an hour." As the door of the room closed, the girl began counting the seconds which must pass before the outer door shut.

"Sixty-two—sixty-three—she ought to be gone!" Clo was whispering, when her heart sank. The room door opened. She feared that Sister Lake had changed her mind; but it was the Angel who came in.

"I was racking my brain how to get rid of Sister when I saw her go out," Beverley said. "I'm sure you managed it. I've been desperate. You can't think what things have happened! Tell me, did all go well?"

The blow must be struck. In a few words Clo described the scene at the Westmorland; told how the ferret-man had kept her waiting; how he had said that the envelope looked all right, but had insisted upon opening it; how he had flown into a rage at finding only folded sheets of blank paper.

"Blank paper!" Beverley gasped. "But that's impossible! I know what was in the envelope. There were letters. The man must have tricked you."

Clo shook her head.

"I was watching him. He had no time, or chance, to play a trick. The blank paper was there, and nothing else. It was writing paper, quite a lot of sheets that seemed to have been taken from some train, 'Santa FÉ Limited,' or a name like that."

Beverley gave a cry, as if she had been struck over the heart.

"Let me think," she groaned. "How can that have been? Writing paper taken from the train?"

Suddenly she turned, and came back to the bed, putting out her hands in a groping way to Clo. The girl caught and held them tightly. They were very cold.

"Angel! is there nothing I can do?" she whispered.

Beverley sank on the bed once more.

"My head feels as if I'd been given ether," she said. "I can't think things out clearly. That isn't like me! A terrible day! One shock after another. If I talk to you, will you swear by all that's sacred never to give away one word?"

"I swear by my love for you. That's the most sacred thing I have, except my locket with mother's picture," the girl answered.

"You see," Beverley went on, "I've no one else but you, Clo. If I told my husband anything, I should have to tell all. I daren't do that. Not because I couldn't trust him. But I've taken an oath ten times more solemn than the one you took just now, to keep a secret that isn't only mine. Another's life depends on the secret being kept. To save that life I was forced to do what I hate to think of. And it's no concern of yours, but it would be Roger's if he had the faintest inkling! Now, I'm going to tell you one or two things, and you must use your brains to explain the mystery. You're clever, and true as steel. You've proved that! Suppose a case; suppose you'd undertaken a dangerous mission. You have in your charge some documents which could make or break a man. You know you'll be followed. You nearly miss your train, but you jump on board at the last minute. You see a man—not the one you expect, but another just as much to be feared—more, perhaps, because he's a great deal cleverer, if not so violent. You think you're lost, but you find a friend, a man who helps you. You give him the envelope that has the papers in it—a sealed envelope. You've seen it, Clo! He keeps it through the journey. At a stopping place on the way he offers to hand it back to you, but you refuse. You feel that the thing is safer with him. Later, in New York, he returns the envelope intact, the seals unbroken. This friend who comes to the rescue is the soul of honour. Never since that moment has the envelope been out of your own keeping. Yet it is opened to-day for the first time, and the papers that were in it are gone, changed for stationery of that train, the 'Santa FÉ Limited.' How can this have been done? Who did it?"

"The other man must have done it, the one who followed you on to the train."

"But he was never near Rog ... never near the man who ... oh, I might as well tell you right out that it was Roger who kept the envelope for me. I'll tell you the name of the other man, too. It's sure to slip out! His name is Justin O'Reilly."

"O'Reilly?" Clo echoed. "How dare the brute have a name like mine?"

"Why, so it is like," said Beverley. "But there's an 'O,' and he spells it differently."

"Beast! He'd better, or I'd have to change," snapped Clo. "Well, whatever his name is, I believe he must have stolen your papers. Can you go back, and live over again every step of the way?"

Beverley shut her eyes, and began to think aloud. "The morning after we started Roger mentioned meeting an acquaintance ... a man named O'Reilly. He didn't dream the name meant anything to me. They exchanged only a few words when Roger passed O'Reilly's table at breakfast time. Nothing could have happened then, I know. Afterward, I never heard of their meeting again through the whole journey. I should have heard, if they had, I think. Roger was with me a good deal. At Chicago.—Let me see!...

"I'm calling it back to my mind. Roger helped me out of the train. O'Reilly was out already. He stood on the platform, looking for someone—or so it seemed. We went quite close to him, but not close enough for even the smartest pickpocket in America to steal the envelope from Roger."

"Where was the envelope then?" the girl wanted to know.

"In an inside breast pocket of Roger's coat; not an overcoat. It was September. The weather was hot."

"Wouldn't it be easy for any one looking for the envelope to see that Mr. Sands had something thick and long in an inside breast pocket, and suspect what it was?"

"Any one might suspect. No one could be sure. It would have shown more plainly if Roger had worn his coat buttoned. He didn't, on purpose."

"Still, his coat not being buttoned would make it easier to steal the envelope, if somebody very clever got a chance to try."

"Perhaps. But O'Reilly could never have done such a thing. It would take a trained thief."

"Can people send off telegrams from those Limited trains?" Clo took up her catechism again.

"Yes, of course they can."

"Would there have been time for this O'Reilly chap to wire Chicago, after he followed you on board the train, and have a man meet him?"

"Yes, plenty of time."

"Well, what if he wired to some detective people, and told them to send him the 'smartest pickpocket in America'?"

"But ... the police couldn't ... wouldn't ... do such a thing!"

"I don't mean the real police," Clo explained. "Haven't you often read books about private detectives? I have. They might get reformed thieves to work for them. Can you remember what O'Reilly did next, after you both passed him on the platform?"

"No. I didn't look back."

"You don't know, then, whether the person he seemed to expect ever turned up?"

Beverley shook her head. "Roger and I went straight ahead to a newsstand where I expected to meet a person. Two or three minutes after we passed O'Reilly we were mixed up in a big crowd, almost fighting our way through...."

"Oh, a big crowd!" Clo broke in. "A chance for that pickpocket. Suppose he came the minute you had turned your backs on O'Reilly, and he sent his trained thief after you, hot foot, to get that envelope?"

"Ah, but you've forgotten something!" cried Beverley. "A thief might get the envelope: I'll admit that. But how could he have another one exactly like it, with the same seals, the same monogram, to put into Roger's pocket, when he took the original?"

"He could only have it if O'Reilly could have given it to him. Could he have done that?"

Suddenly Beverley began to see. A vivid idea sprang into her head, and was imaged in her eyes.

"You've thought of something!" Clo exclaimed. "You see how O'Reilly might have got the seal with the monogram, and the gold wax, and an envelope like the one you had?"

"Oh, yes. I do see!" Beverley groaned. "He could have brought the things from—from.... But never mind. That part's nothing to you."

"I want only to know the part you want me to know," said Clo.

"It isn't a question of what I want. It's a question of my sacred oath," Beverley answered. "There was a house where I had been, to get the envelope. O'Reilly was there, too. Someone ... no matter who! ... could have given him all the things, so he could change envelopes if he got the chance. Oh, child, I keep stumbling on to a path where I dare not step."

"We'll go back to the train," said Clo. "If O'Reilly had the gold wax and the seal, and the right kind of envelope, he could have made his plan, and sent his telegram, and had everything ready for the right minute ... in the Chicago station."

"Ye—es, he could. But it's almost impossible!"

"It's more possible than Mr. Sands' changing the envelopes, isn't it?"

"That is the one impossible thing. The worst remains. I have lost the papers! Whether O'Reilly has them or someone else, I can't get them back. Without them, I'm ruined!"

"You shan't be!" Clo cried, twining her thin arms round her idol's waist. "You must be saved somehow. We've got till ten o'clock to think."

"If I were the only one, it wouldn't matter so much," Beverley said. "But there's somebody who can be tortured as well as killed, if I have no bribe to offer. Those papers gave me all the power I had."

"Wouldn't money...." Clo began, but Beverley cut her short.

"No money I could get would be of any use," she said. "A million might be!"

"See O'Reilly and make him give up the papers!" cried Clo. "Oh, but is he in New York?"

"He doesn't live in New York, but he's here now. I know, because that man you saw, Peterson, told me. It was part of a threat he held over my head that O'Reilly and some people connected with him should be in town just now. I know the hotel he's staying in, the Dietz. But even if O'Reilly would come, how could I see him without Roger knowing? It wouldn't be possible!"

"I'll somehow make O'Reilly come," the girl promised. "I don't know how, yet, but I know I will, if you can get Mr. Sands out of the house."

Beverley shuddered. "How horrid that sounds ... as if I were plotting against him, the way women do who deceive their husbands."

"Well, anyhow, if O'Reilly took the papers, would he still have them, do you think?" asked Clo, with the sudden eagerness of one who catches in desperation at a new idea.

"It's just possible. I can see a reason why he might have been asked to keep them," Beverley answered.

"If that's so, would he put them in a bank, or a safe somewhere, or would he bring them to New York?"

"There might be a special motive for him to bring them to New York ... I think there would be a motive."

"Well, it seems to me, the sort of man I imagined he is, would be too smart to have such things on him if he came to your house, and didn't mean to give 'em back to you. It would be tempting Providence, so to speak!"

"If I were the kind of woman he thinks I am, he'd not expect me to stop short of murder to get those papers," and Beverley laughed a bitter little laugh.

"Good! If he comes to you and leaves the papers at his hotel, a certain thing will happen, but it's safer for you not to know—till afterward."