The episode's cold open depicts a scene from 1933 in which Herrick and Mitchell discuss what it means to be a protegé. George learns his father has died, surreptitiously returns for the funeral, and reconciles with his father (guest star James Fleet)—who, it turns out, isn't dead. He moved out when George's mother began an affair with another man, and faked his death. George visits his mother, and is bullied by her lover. He later tries to reconcile his parents. DC Nancy Reid (Erin Richards) begins investigating Mitchell for the Box Tunnel murders. Mitchell tries feeding his own blood to Herrick, but this fails to awaken his vampirism. But he later feeds off a bloody tissue left behind by Reid. Annie learns that Lia (the ghost from Series 3, Episode 1) was one of the Box Tunnel victims, but Mitchell denies knowing her. Annie starts to help Reid solve the murders, but unwittingly leads her to suspect Mitchell.