Sgt June Ackland and PCs Jim Carver, Tony Stamp and Polly Page are trapped in a cellar, and with Jim's wedding to Marie Graham only hours away, tempers start to fray amongst the group as old tensions boil to the surface. A leather-clad biker who turns up at the station turns out to be the new Detective Constable, Juliet Becker, who is paired with Mickey Webb when PC Gary Best realises that four Sun Hill officers have gone missing. It's a race against time, as a gas leak threatens the trapped officers, but Webb and Becker manage to rescue them in the nick of time. Despite his discussions with June Ackland in the cellar in which she asks him to call off the wedding, Jim and Marie get married. PC Luke Ashton is terrified that Sgt Dale Smith will ""out"" him to the rest of the relief - Smithy is non-committal, but it's Ashton's estranged wife Kerry Young who reveals his secret at Jim's wedding reception.