Smithy's day goes from bad to worse when a fight that brakes out in custody during a power failure turns into an attempted murder, when one of the prisoners is stabbed with a knife. With only four suspects who could have possibly committed the crime, the team attempt to work out which one of them could be responsible for the attack: David Coles, the husband of Perkins' ex-wife, who firstly assaults him and then Walker after he discovers Perkins' illicit affair with his wife; Julie Knights, the best friend of the victim; the victim's flat-mate, Ollie, who turns out to be the Army sergeant of her deceased son, and a woman who claims she is unable to even remember her own name - or can she?