This chapter opens with a flashback to the previous chapter, in which the two young men discuss the possibility of killing each other. The flashback is interrupted by the sound of a knock at the door, and the young men realize that the professor is not in his usual hiding place. The young men wonder why the professor hasn't been in his hiding place since the last time they saw each other, and they realize that he's been gone for three days. They wonder if it's because of the curse of the mud on the professor's statue, or because the statue is stained with lime juice. They realize that it must be the same thing, because there's a sign on the bottom of the box that says, "The bottom of this box contains the blood of the murderer." They wonder whether this is a coincidence, or if the blood in the box is the same blood as the blood from the murderer in the hospital. The two men wonder if this means that they'll still be working with the murderer, and that the grudge between the two sisters will still be there. The men wonder whether the blood sample