Stingers

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.

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.

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.

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.

Moonlighting as a private eye for an old friend, Tom Barton, Church is labelled a suspect when Tom is found shot dead. Church ignores all warnings to stay well away from the case and delves into the complicated world of Tom's clientele, learning a few secrets along the way.

In this episode Church goes undercover in a bike gang to bust them on drug dealings. However, when the unit realises, after a fight and a murder, that the gang is at war with another bike gang, the pressure is on Church to stop an all out bloodbath.

The future of the Undercover Unit looks uncertain when Stone is investigated for the shooting death of a biker. Internal Affairs leaves no stone unturned in its investigation of the incident, leaving Church to choose his loyalties when Mackenzie attempts to rally the unit to save Oscar.

In the aftermath of Bill Hollister's murder, Church goes on a crusade to catch who he believes is responsible. Angie visits her sister only to discover a tragic secret, and Mackenzie grapples with her feelings and how to face Hollister's family.

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.

The Undercover Unit investigate a disturbing ring of criminals, who use an internet chat-room to procure their victims. Danni pulls Church into her personal quest to prove a traffic offence has been covered up while Angie tries once again to help her sister beat her drug addiction.

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

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.

Danni's life and career is threatened when an escaped criminal seeks his revenge. Danni is at first reluctant to admit to Mac that she's being stalked as she's afraid she'll be forced to leave the unit due to compromised security, however she eventually confides in Mac and an investigation is set up to determine where he is hiding.

In a case which has personal resonance for MacKenzie, the Undercover Unit stage an intensive investigation, determined to nail a certain murderer.

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

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. Unlike the others, Church actually likes the job, and the stories people have to tell, and when he takes a fare from a highly agitated young man, he hears a story to beat all stories.

As the unit investigate a private detective who specialises in adoption cases and has been accused of providing phoney relatives, Mac goes undercover using her own profile with the secret hope of finding her birth mother. The question is: after he's completed his investigations and he produces a woman he claims to be her mother, will she be Mac's real birth mother or just another phoney?

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 makes contact with her natural mother and both women become embroiled in an Undercover operation to nail a mastermind armed robber.

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

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.

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.

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.