An odd-looking, wounded dinosaur leaps through an anomaly in a scrapyard, pursued by a medieval knight, who thinks it is a dragon and causes havoc in the high street during a carnival, believing he is in Hell. Whilst Abby patches up the creature's wounds, Sarah steps back in time through the anomaly to discover that the knight is William de Mornay, seeking redemption for his sins by slaying a dragon and on her return persuades him to spare the dinosaur and return home. Connor meanwhile takes drastic action to retrieve Abby's pet Rex, lost in a card game by her brother.