"I supposed that he had brought the body to the shore of the river in a boat, and was carrying it to one of the doctors in the hospital. "We allowed him to pass us, and then we followed him. He went to the wall surrounding the hospital grounds. "Choosing a place where there is a bank of rubbish against the wall, he lifted the sack to the top. Then I knew that it could not contain a dead body." "How did you know that?" asked Nick. "Because he lifted it so easily. What was in the sack I do not know, of course. There was some crooked business about it, I have no doubt, but it was not a body that he had there, because, by the way he handled it, I saw that it could not weigh over fifty pounds, and the sack was too large to have only a child's body in it." "What did you do?" "We watched him lay the sack on top of the wall, and then climb up. He dropped the sack into the garden, and let himself down from the wall. We paid no further attention to the matter. "It made Margaret very nervous, but I proved to her, by the weight of the sack, that her suspicions regarding its contents were unfounded." "Did you know the man?" asked Nick. "I hardly like to answer that question." "Why not?" "I am afraid of doing somebody an injustice." "You have a suspicion, then?" "I have." "Was the man Dr. Jarvis?" "I cannot say. I do not know him." "But his dress--" "I see that it is useless to try to conceal anything from you," said Prescott. "The man wore the peculiar cap and dressing-gown which everybody knows for the doctor's." "There is no doubt about it," said Miss Allen. "It was Dr. Jarvis." "I thank you very much for your evidence," said Nick. "But why do you want it?" asked Prescott. "I have heard a rumor that Patrick Deever has disappeared. This is his brother's house. Is the doctor suspected of having murdered him?" "He is," said Nick. "Then I see the bearing of my story upon the case; but I assure you that that bag did not contain Patrick Deever's body. It was too light." Prescott spoke with decision. Out of the corner of his eyes Nick could see Chick struggling with this phase of the evidence. Chick was too good a detective not to know that one little fact of that kind is worth a hundred that lie too near the surface. "You can do me only one more favor," said Nick, addressing Prescott and Miss Allen. "Do not under any circumstances mention what you have seen without my permission." "You can trust us for that," said Prescott, with a smile, "we are by no means anxious to have our connection with this affair made public." The two witnesses withdrew, leaving Nick and Chick together. They were silent for several minutes, and then Nick said: "Well, Chick, the chain is complete." "It is," was Chick's reply, "and in all my experience I have never seen a plainer case made out against any man." "You mean from a jury's point of view." "Certainly." "What do you think of it?" "I wish you'd tell me just what you think of it, Nick."