London is in the grip of winter, and the Westfield Comedians troupe is out of work. The actors happily accept the invitation to perform in Essex, despite the fact that they are given two conditions: they must show a new play and accept new student Davey Stratton into the troupe. At first, it seems to everyone that Davey sincerely dreams of becoming an actor, but he begins to quarrel with other students, and soon even runs away. Prompter Nicholas Bracewell does his best to help the troupe thoroughly rehearse their new play, The Witch of Colchester, but when one of the leading actors falls victim to the strange ailments that his character suffers from in the play, some of the comedians begin to suspect that among a witch is hiding among them. The matter is further aggravated by the fact that during the performance one of the spectators unexpectedly dies, so Nicholas has to investigate strange events in order to expose an insidious conspiracy. The novel "The Devil's Disciple", rich in historical details, captivatingly tells about the golden age of the theater.