S4·E6 Episode 6

Two boys break into a boat moored in a marina and take out the cooking gas cylinder to sniff it. Alerted by an alarm, a security guard goes to investigate. One youth escapes, but the other is still sniffing when the guard turns on the light, causing a huge explosion. When the Watch arrive, several boats are on fire. Kevin spots the security guard in the freezing water and dives in without a line. Nick then has to dive in to rescue Kevin and see the mutilated body of the second youth floating alongside them. George learns that he is going to be a father but Nick is fed up with the constant pressure for him to marry cousin Ariadne. Colin and his uncle Jaffa taje their revenge on Technique who has sold them a dud window-cleaning round. Marion finally realises Technique is a rat and tries to make it up with Kevin. When he won't have anything to do with her, she takes pills and vodka and is rushed to hospital.