While checking on a sick sheep farmer, the Doc runs into Stewart James, a patient who used to suffer from delusions that he lived with a giant squirrel. Stewart is now starting a survival course business, and he invites Al and PC Penhale to join him in the woods for a test run. But when Stewart begins to behave oddly, Al worries he's having a mental breakdown and must figure out how to get help. Guest starring Ben Miller (Death in Paradise).