The undercover Unit face a psychological challenge when an operative loses his identity during a long-term assignment.

A sassy new operative arrives at the Unit just as the group go undercover to entrap a gang of teenage thieves. However, a mistake leads to as kidnapping which places everyone in jeopardy.

Church goes undercover into the world of stolen art. When he discovers that the target is abusing his son, Church's repressed memories of his abusive father are triggered and he must grapple with conflicting emotions.

A well planned sting goes horribly wrong when Church infiltrates a criminal gang who are intent on robbing a very large bank.

Angie's assignment is jeopardised with the unexpected arrival of her sister. Mac is faced with a crisis when she discovers that Danni is involved with a suspect.

Danni's future with the unit is on the line when her ex-boyfriend becomes the prime suspect in a horse-doping scam.

Hollister asks Mac for help to capture master bank robber, Marty Stockwell. Hollister wants revenge after Stockwell fatally shot one of his men. Church and Danni go undercover to bring Stockwell to justice.

In court, things go horribly wrong when the Magistrate dismisses the charges against Tony Howarth for shooting Bernie Rocca. Church comes under fire from Internal Affairs after he is accused of using excessive force to obtain a confession.

Church becomes involved in a young boy's life after he catches him trying to steal his car. Meanwhile, Angie goes undercover to expose a dentist accused of malpractice.

Three backpackers are murdered. Stone is sent in to investigate the suspect, Evelyn Leigh but he lets his emotions cloud his judgement - a mistake that could cost him his life.

Mac and Church must infiltrate a neighbourhood residents group who are protesting the acquittal and return to the neighbourhood of a local teacher recently charged with the murder of a young student.

When Church conducts a sting on a bikie gang, a simple gun deal becomes complicated after Church is hired to do a hit.

Church strikes up an unlikely friendship with a hitman after preventing his attempted suicide. He is drawn into the middle of a heated triangle with no simple solution.

Danni learns the meaning of betrayal when she is forced to use an innocent to solve a murder.

MacKenzie faces a dilemma when Detective Inspector Bill Hollister is revealed as a regular client at an illegal brothel.

Danni and the rest of the team are called in when a well-known career criminal turns Crown witness under unusual circumstances.

MacKenzie's past comes back to haunt her when her adopted brother is released from prison.

While working to exposed and armed robbery ring, Angie is stalked by an obsessed admirer. The stalker not only jeopardises Angie's sting, but threatens the security of the entire unit.

Church must put his career on the line when an old Academy buddy is implicated in a homicide.

A personal favour from Church becomes a case for Undercover when an illegal organ-trading scam is exposed.

The Undercover Unit are assigned to investigate a five-year-old unsolved bank robbery with tragic consequences.

MacKenzie and Angie face an internal Affairs investigation when an informant commits suicide.