As Church, Danni, Stone and Angie focus on a drug sting, Mackenzie is distracted by an invitation to apply for Head of Homicide -- which would mean leaving the Undercover Unit.

Church's worlds collide when he has to attend his twenty year high-school reunion as part of a drug sting. Danni learns she is pregnant.

Stone and Gray are caught in a siege at a hospital when an armed robbery goes horribly wrong. Meanwhile, the rest of the unit need to try and gather information about the armed robbers to regain control of the situation.

The Unit works with an undercover operative from Queensland to defeat a gang of amphetamine dealers responsible for a kidnapping.

Church tags an unconvicted robber/murderer in the hope that he will lead them to unrecovered bank funds, while Angie and Stone try to locate a missing accomplice. Meanwhile, MacKenzie has news on her birth mother.

MacKenzie investigates a private detective who specialises in adoption cases with the secret hope of finding her birth mother.

Following a spate of violent robberies, Church and the others are placed undercover as taxi drivers, in hope of catching the offender in the act.

A case of mistaken identity during a botched raid at a nightclub results in Stone being recruited to assist with a major armed robbery.

Danni's life and career is threatened when an escaped criminal seeks his revenge.

A surprise turn of events provides the Undercover Unit with a tangible link to Hollister's murderer, while Stone finds himself recruited to undertake the most daunting of tasks.

A surprise turn of events provides the Undercover Unit with a tangible link to Hollister's murderer, while Stone finds himself recruited to undertake the most daunting of tasks.

The Undercover Unit find themselves battling a race against time when called in to investigate an extortion attempt against a pharmaceutical company.

The Undercover Unit investigate a disturbing ring of criminals, who use an internet chat-room to procure their victims.

Church and Danni pose as foster parents in an unusual operation to capture Australia's most wanted armed robber, but ultimately get more than they bargained for.

In the aftermath of Bill Hollister's murder, MacKenzie grieves while Church tries to bring the killer to justice.

The future of the Undercover Unit looks uncertain when Stone is investigated for the shooting death of a biker.

Church goes undercover as a bikie to expose a major amphetamine ring linked to The Living Dead biker gang.

Moonlighting as a private eye for an old friend, Tom Barton, Church is labelled a suspect when Tom is found shot dead.

Mackenzie and Church pose as a feuding couple, while investigating the disappearance of a man while visiting a health spa where couples go to heal their ailing marriages.

With what is feared to be a serial killer at large, the Undercover Unit is asked to gather evidence on a man recently released from prison after serving time for assault.

Drastic measures are taken to allay the suspicions of a drug syndicate and win their confidence. Meanwhile, Mac has to decide whether to accept a romantic proposition.

Mackenzie and Hollister are called to investigate a homicide at the docks. Church works undercover as a customs officer when the unit has been called in to investigate the deaths of 11 illegal immigrants found inside a shipping container.