Safe breakers break in at Adams Brothers. One of them accidentally activates the alarm just as PC Mason passes on his motorbike. They manage to get away, but the next day their driver is found floating around dead in Whitby harbour. Is this the revenge of his accomplices for leaving them when the alarm went off or...? PC Mason also suspects it was an inside job because there was an exceptionally large amount of money in the safe. Meanwhile the rest of the gang stays comfortably at the Aidensfield Arms planning how to get another crack at the safe. It is Dawn's birthday and Gina organizes a surprise party for her. But Dawn is not the only one who gets surprised. Alf and PC Younger wonders why PC Wetherby disappears every day at lunch break and Oscar Blaketon bets them £5 that he can find out in a matter of hours. He gets a surprise too.