At his countinghouse, Quilp’s wife brings him a strange letter left by an anonymous boy. The letter turns out to be from Sally, detailing her flight from London and urging Quilp to run too, now that the truth is out.

Quilp chases his wife away, losing sight of her in the fog. He shuts and latches the main gate behind him just as someone begins to knock violently. Thinking it is his wife trying to get back inside, Quilp ignores the knocks and tries to return to the countinghouse. The fog, however, is too thick, and he cannot find the way. The knocking continues, and Quilp, disoriented, turns the wrong way and falls into the Thames River. The current is too fast for him to fight, pushing him below the surface again and again. Each time he comes up, he hears the knocking and recognizes the voices calling for him, but the locked gate prevents them from either arresting or saving him because. When a ship overruns him, Quilp cannot make it back up to the surface and he drowns.