Greengrass is asked to put on a number of bets at the races for some rather unscrupulous characters. But before he gets the chance he ends up in hospital with a suspected appendix problem. Blaketon is afraid he'll have to retire and is tempted when Arnold, his friend offers him a job. A young boy has been assaulted and Nick suspects Arnold - Blaketon strongly disagrees. Nick investigates and finds evidence to suggest that Arnold could also be guilty of corruption. He ends up having an argument about it with Blaketon, who then storms out. Nick realises he's offended him and goes round to apologise. Meanwhile Blaketon has a chat with Arnold and realises Nick's right.