It is Katie's christening, and everyone is celebrating at Nicks house afterwards, when an old girlfriend of his, Gill, from the Met turns up for a visit. Nick and Gill are asked to go undercover to investigate the criminal activities of the owner of a well known gambling club. Blaketon thinks that Mr Armstrong is going to cheat in an up coming racing event by tampering with the favourite horse, ‘Fab Four'. The police are on to him, and he soon notices he's being watched so he kidnaps Gill and hides her in a horse box. Nick and Phil come to the rescue.