The police are unable to find Hyde and Jekyll's mood seems to improve and he becomes sociable again for the next couple of months. Suddenly he becomes depressed and withdrawn and Utterson becomes concerned for him.
Utterson visits Lanyon to discuss his concerns but finds that Lanyon has become very ill and is on his death bed. Lanyon will not discuss Jekyll, but he suggests that Jekyll is the cause of his illness.
Lanyon dies soon after and leaves a letter to Utterson that is only to be opened on the death or disappearance of Dr Jekyll.
Utterson, being a good lawyer, locks this away in his safe. Utterson tries to visit Jekyll again several times but his servant, Poole, says he is living in isolation and will not see anyone.
Utterson and Enfield, whilst out on one of their walks, pass by Jekyll's window and see him. He looks like a prisoner in solitary confinement. Utterson calls out to him suggesting that he joins them for a walk. Jekyll declines and his face suddenly freezes in an expression of "abject terror and despair". This change is so sudden that it "froze the very blood of the two gentlemen below". The pair leave in silence.