Blackmailer Peter Retford phones Susan's client Harry Johnson and Charlie to 'remind' them of past financial discrepancies and, after Charlie is forced off the road and one of Retford's heavies is hospitalised due to Harry, Jim investigates. However he is suspended after being tricked into appearing drunk. This makes Charlie confide in him how he once fixed a building contract and, with things in the open, Charlie agrees, along with Harry, to help Jim trap Retford. (thetvdb.com)