It is Poole's opinion that Dr. Jekyll was "made away with" at that time, and whoever is in the room now is "a thing known only to heaven."
Utterson tries his best to be rational about the mystery. Logically, he says, if someone had murdered Jekyll, why would he still be in there? Poole then explains more about whoever is in the room. "Whatever it is," he says, it "has been crying night after night for some sort of medicine." Earlier, Jekyll used to cry out for certain medicines and would write his orders on a sheet of paper and throw the paper on the stairs. For a week, there's been more papers on the stairs, a closed door, and whimpering. Poole has done his best to find the exact medicine, but no matter what he has brought back, it has not been "the right stuff." "It" always says that Poole has brought something that is "not pure" and, therefore, Poole has continued to receive orders to go on yet another errand to yet another store. "The drug is wanted bitter bad," Poole tells Utterson.
Utterson asks for some of these notes, and Poole is able to find one, crumpled up in one of his pockets. At first glance, the note seems to be merely a formal request — nothing amiss — asking that the pharmacist search for the drug "with the most sedulous care." Expense is no consideration, the note stresses, and there is a sense of urgency: "The importance of this to Dr. Jekyll can hardly be exaggerated." And then in a scribbled postscript, there is: "For God's sake, find me some of the old [drug]."
Utterson finally has to admit that this is indeed murky business. More than murky, says Poole: "I've seen him," he adds, referring to whoever lurks behind Jekyll's door. One day, Poole says, he came into the large room just below Jekyll's private room and there, digging among some crates, was a creature who was so startled at seeing Poole that he cried out "and whipped upstairs." If that were Jekyll, why did it run? Why did it "cry out like a rat?" And why did it wear a mask?
