Flynn's old flame guides him deep into the world of body art, heroin and murder.

Angie and Harris face every parent's nightmare when their son Josh falls victim to a child abduction ring.

Harris goes undercover as a translator for a Malaysian drug cartel and descends into a world of opium smoking and prostitution.

Church risks radiation exposure in a desperate attempt to avert the detonation of a dirty bomb.

Three homeless men have been murdered, and Church goes undercover into the homeless community to track down the killer. Without the back-up of weapons or communication, Church submerges himself in this shadow world. But he quickly learns that murder might not be the only thing going on, someone is making what look like snuff movies, featuring the murdered homeless men.

Betrayed by an old love, Church faces execution at the hands of a drug dealer.

Church and Gray fake the death of two people in order to sting an elusive crook known as the Coyote, only to discover they might have targeted the wrong man.

He's killing innocent tourists, now Angie goes face to face with evil ...

Angie pursues a journey of revenge after the shocking murder of her sister.

After meeting up with an old friend, Chris is horrified when he commits suicide and tries to prove the incident was murder.

An investigation of a liquor store robbery takes an unexpected turn when one of the gang members claim they are being protected by ""The Walrus"", a corrupt cop. Harris suspects that the Walrus is the Head of Armed Robbery, Geoff Skinner. When Megan Walsh reveals that Skinner is her old friend and mentor, Harris begins to suspect that she may tip Skinner off, and his suspicions are heightened when Megan starts asking him questions about the case after seducing him. Meanwhile Katherine suffers an extreme bipolar episode and Harris is forced to confront the fact that their relationship is at breaking point. Katherine leaves for a posting in WA, leaving Harris shattered.

When Harris and Masters locate a massive quantity of cocaine in the boot on an imported U.S. Mustang, it looks like they're on the verge of a huge arrest. But things go haywire when the importer of the vehicle, property developer David Cale, refuses to take possession of the vehicle due to a small rust problem. Suddenly Harris and Masters are left holding a whole lot of coke with no-one to bust. Masters soon pulls the pin on the operation leaving Church undercover in the importer's garage without any back up. When the bad guys come calling looking for their cocaine, Church finds himself in a very sticky situation with no way out.

Church has established himself as the muscle in a close-knit Italian crime family, prolific producers of methamphetamines. When the head of the family discovers that his son has been seen in the company of a cop, he takes the cop hostage and orders Church to kill him. Church is horrified to discover that the cop is Harris, and that Harris has been buying opium off the son. Church manages to fake the shooting, but the son soon tracks Harris down. As the Undercovers move in to bust the family, Harris is finally forced to make a choice between his addiction on one hand, and his career and family on the other.

Chris convinces a young prostitute to give her information about a blackmail scam at a brothel. The client she names refuses to talk, and then the prostitute is found with her tongue cut out. Angie goes undercover in the brothel as a cleaner, and is surprised to discover that Reg Masters sees a dominatrix who works there. A mortified Masters agrees to go in wired and use his relationship to set up a cocaine buy with the owner, who is none other than Steve Wylie. Wylie is brought down, which leads Harris to consider the recent events surrounding the death of Wylie's brother, who undercover believed to be a major player in the criminal world. Harris enlists Angie's help to investigate his theory that Megan Walsh is corrupt. Church refuses to consider the possibility, and it soon becomes clear why – he and Megan are lovers. Harris is forced to offer proof of Megan's treachery – she slept with him for information.

While on a deep cover operation, Church is intercepted by a couple of thugs and thrown off a building. Waking in hospital with minor fractures and head trauma, Church discovers his memory has been completely wiped. He can't remember his name, how he came to fall from the roof, or anything of his past. The only clue is his driver's license, which names him as Josh Brisbane. Church soon learns Josh Brisbane is a gun for hire, contracted to take out underworld crime figure Nick Tascone. While his instincts tell him to cut and run, a confrontation with his target becomes inevitable as Tascone moves to finish the job of terminating his would-be assassin.

When Church misbehaves on a drug bust and is accused of corruption by an unnamed informant, he is investigated by Internal Affairs. The Undercover team unearth evidence that an IA cop is framing Church, but Harris orders them to draw a line under the investigation. Instead, he sends Megan to search Church's house, where she finds stolen goods - damning evidence that Church is corrupt. Church admits his corruption to her and in turn she admits her own. Together, they devise a plan to rip off the drug bust cocaine and escape. When Church is arrested for possession of stolen goods he and Megan are forced to bring the coke deal forward. It is only when Harris arrives at the scene of the deal that Megan realises it's a sting, and that Church is wearing a wire. She stares at Church in disbelief as she is arrested and taken away.

The city erupts into violence as underworld gang members start knocking each other off - but with Flynn and Church undercover in the rival gangs, how long before one of them becomes a target?

Angie goes undercover as the long lost daughter of contract killer William Franks. A notorious assassin, Franks hasn't seen his daughter since she was a three year old and he was imprisoned for the murder of his wife. Though Angie initially has no qualms about such a deception, as she comes to know Franks she comes to believe that he's not the monster she first thought. When evidence comes to light suggesting Undercover has been wrongly targeting Franks for an intended hit on anti-Islamic pop philosopher, it appears that Angie's suspicions of Franks' innocence may be true. It's only at the eleventh hour, in a hostage situation, that Angie discovers Franks' true, heartfelt purpose.

The murder of an illegal immigrant leads to an undercover brothel trading in sex slaves and a missing girl suffering from Stockholm syndrome.

When Chris is involved in a car accident after a night on the town she is horrified to discover a nine year-old boy was seriously injured. Chris questions her own culpability given that she hadn't slept and her reaction times were down. Her problems escalate when the boy's mother claims Chris was in the wrong and she intends to sue. Chris doggedly pursues every lead to prove her innocence, and in the process discovers evidence that the boy's doctor may be faking medical records in order to fraudulently claim accident compensation. When Harris shuts down the investigation Sophie takes matters into her own hands and goes undercover as a patient. Fortunately her audacious move pays off and the doctor is brought to justice. Meanwhile, Harris starts to feel threatened as Angie and Sean Hunter take their relationship to the next level.

Harris' obsession with Angie's new partner spirals out of control when one of the Undercover unit falls victim to the serial killer.

Angie frantically tries to clear her lover's name while Harris works equally hard to convict him as the serial killer. Convinced Sean Hunter is innocent of the attack on Sophie, Angie sets out to exonerate the man she loves and catch the real serial killer. She suspects Richard Kline, who blames Hunter for the suicide of his wife, a former patient of Hunter's. Chris goes undercover on Kline, which leads to the discovery of trophies from the previous killings on Kline's premises. Hunter is freed and an already off-centre Harris, realising he has lost the battle, slips into bipolar meltdown and is forcefully taken into emergency psychiatric care. As the current is administered to his temples we go out on Angie and Hunter happily making their wedding plans. As they tenderly embrace, the cold disregard on Hunter's face tells us that Angie has become victim of a very lethal deception.