Heartbeat S07E21 - The Enemy Within

Blaketon receives a visit from his army sergeant, Jim Ryan. It's the happiest of reunions - until Blaketon realizes Jim is losing his mind following his wife's death. As Blaketon begins unravelling long-buried secrets from his sergeant's past, an unhinged Jim targets a pair of young photographers - and Mike Bradley, leaving Blaketon with a terrible dilemma. Meanwhile, Greengrass calls on Ventress for help when he is conned into buying stolen sheep.