Mackenzie becomes the victim of a grifter on the eve of her interview for head of homicide, while Church finds his career threatened.

Angie faces one of her toughest cases yet when she has to develop a romantic relationship with a murder suspect and then coerce him into becoming an informant.

Danni's determination to go it alone with her pregnancy clouds her professional judgement when she stumbles across an illegal adoption racket.

Mackenzie discovers the grifter who drugged her is linked to a senior colleague - someone who has good reason to want her out of the running for head of Homocide.

Stone cultivates a live-wire young prostitute named Brittany to get information on a dangerous drug crime.

Church is sent undercover to share a cell with a convicted murderer.

Angie is forced to bend the rules as she attempts to prevent her sister Sam from being arrested on drug importation charges.

Danni has to protect and help prepare for the court appearance of former undercover cop Gary Edgerton, the reluctant key witness in the trial of a major criminal.

Stone investigates a woman who may just be organising a hit on her husband, while Mackenzie is dealing with hitmen of a different kind.

Angie and the rest of the Undercover Unit rally around Mackenzie, risking their jobs in order to prove her innocence.

With Harry Love in a position to make his final move against Mackenzie, she and the Undercover Unit are forced to take desperate action, with tragic consequences.

Undercover teams up with Armed Robbery to bust a violent robbery ring. Church infiltrates the group but is forced to bow out when he is given a shotgun and told to rob a convenience store. It looks like Undercover has blown it—until Angie uses her real-life romance with informant Marty Engle to gain access to the ring, a situation that places them both in dangerous territory.

Stone and Church go undercover to investigate a pair of teenage drug manufacturers, with unexpected tragic consequences.

Stone is abducted when Undercover's attempt to bust an international arms dealing ring, run by lethal ex SAS officers, fails.

When a failed drug bust leaves the Undercover Unit with a dead dealer high class prostitute holding a couple of bags of cocaine, the Unit undertake an operation inside a busy brothel: Gotham City.

When an undercover operation causes the death of a young woman, Church and Angie are faced with the dilemma of saving one dangerous criminal from another.

The Unit's attempts to trap a serial killer leaves Mackenzie fighting for her and her best friend's life.

Stone heads undercover to expose a high powered businessman, but experiences a crisis of conscious when he discovers a young prostitute he has cared for is in danger as a result of his actions.

Church becomes convinced he is being stalked by a man who holds him responsible for the murder of his girlfriend, causing him to jeapordise the Unit's current operation: busting an illegal tobacco ring.

When the Unit try to nab a standover man for murder, Angie's relationship with an informant results in a confrontation within the ranks; the Stingers having to face the fury of one of their own.

The unit seems on shaky ground when homicide attempt to charge Church with murder, but are devastated when Stone goes beyond the call of duty to save Church.

Mackenzie is faced with a choice between her personal happiness and her successful career, when she becomes involved with a charismatic art thief, who entices her into believing that love is more important than the law.