The Metropolitan Police set up a new unit, UCOS, which stands for Unsolved Crime and Open Case Squad, to investigate previously unsolved crimes. Led by Detective Superintendent Sandra Pullman, the team is made up of retired policemen Jack Halford, Brian Lane and Gerry Standing. Their first case is to investigate the murder of a nightclub hostess. The man who was convicted of killing her is released on appeal after serving twenty years in prison, having always claimed his innocence. The renewed investigation eventually produces proof of his innocence, but also his guilt of a different murder. In the end the team finds proof that the man's wife killed the nightclub hostess out of jealousy.

UCOS investigate into the death of a policewomen-whose case was closed years ago-following the recovery of the murder weapon from a lake.

The discovery of a fake painting in the Queen's art collection sends the UCOS team on a hush-hush mission to uncover the forger. Their investigations swiftly uncover a trail of high class frauds and suspicious deaths, but also lead to suspension for one of the squad.

NOTE: In Scotland This Episode Was Shown On Sunday 11th April Due To LIVE Sportscene Football Being Shown

The UCOS team investigate the murder of a young peace protestor, killed at the outskirts of a nuclear base in 1984, and realise that they may be in danger of exposing a Special Branch cover up.

The members of a prestigious golf club come under suspicion when the UCOS team investigate a child murder.

When a missing person case which Lane originally investigated gets re-activated, he's determined to crack it. But when the team swiftly uncover another two mysterious disappearances, they start to think they've got a serial killer on their hands.

In an attempt to make contact with his late wife Mary, Jack goes to see a clairvoyant. Instead he meets a girl who died in a shipping container in 1982 and has the case re-opened.