Brian Elliot, a friend of Ch. Insp. Conway, has been robbed by a prostitute and her accomplice, but does not help the investigation when he refuses to make a formal statement or testify in case his wife finds out about his indiscretion. CID launch an undercover sting, which fails, but Elliot arrives at the station with his wife to make a statement, and it is quite clear she knows the truth.
It turns out to be quite an eventful first day at Sun Hill for new probationers Nick Slater and Debbie Keane.
Sgt. Boyden and probationer PC Nick Slater are called to the house of an elderly lady who claims a couple are fornicating in her garden. A search of the surrounding area turns up the guilty parties: a wealthy local businessman and his companion, Lisa Royle. Drugs are also found in their car, so the two are taken into custody. Lisa flirts with Boyden, and gives him a phone number to call to vouch for her identity. She turns out to be DS Lisa Holm on an undercover operation, and an angry DI Raymond turns up at Sun Hill to ensure the operation is not further compromised. Slater is confused when Boyden suddenly releases the pair and demands to know why, but Boyden tells him that as a probationer, there are a lot of things he doesn't need to know.
A series of unexplained robberies are cracked when one of the victims reveals she was seduced by a handsome freelance car washer, who copied her keys and arranged to meet her later, but robbed her house while she was waiting for him. Despite Insp. Monroe's objections that she is too inexperienced, DC Skase arranges for probationary WPC Debbie Keane to go undercover as a lonely housewife to catch the thief at work. The plan goes well, but at the expense of Skase's car when he uses it to block the driveway to prevent the thief's getaway.