Tactical Response risk their lives to save the injured and find the shooter. But they are up against an offender they know little about and a motivation they can't possibly understand. Shannon braces herself for the ultimate test to her character as she faces off against the shooter.
As Lawson's growing obsession with the robbery crew threatens to pull Tactival Response apart, Josh shows his leadership as TR2 assist Drug Squad with the arrest of a drug importer. But things aren't as simple as they first seem when TR discover the offender's niece has been kidnapped and held to ransom. Josh must race to save the girl, in the process meeting her mother, Tash, who will change everything.
Tactical Response score a lead when an ordinary civilian unwittingly implicates himself with Andrew Kronin's gang. As Lawson pushes the man to get to Kronin, Dom takes umbrage. Dom snaps, turning his gun on TR1 and flees. As TR2 track down Dom, Lawson exults when he recovers a substantial amount of the heist money.
Christian is excited to be protecting one of his favorite childhood Idol's whilst he is on a visit to Australia. However he and the teams become concerned after it becomes obvious the prime-minister is being targeted by an assassin, and Dom is rejected by Lawson after he requests his job back.
The team chase down a young volatile couple who's business has just been liquidated and who are intent on getting married before the man is sentenced. Elsewhere, Stella tries to reason with the owner of a bar with ethnic issues and Josh receives a cry of help from Minka, Tash's daughter, which rekindles Josh's interest in Tash.
In trying to get more information on Kronin's gang Michael enters the world of underground boxing but ends up being identified as TR and inadvertently putting his life in danger. Meanwhile, as the team track Kronin's gang to a warehouse Shannon ends up saving Kronin's life when he is nearly attacked by a vengeful ex-associate and she ends up being kidnapped by Kronin. Elsewhere, Michael takes the plunge and asks Audrey out for a drink.
Josh and Lawson board a suburban runaway passenger/freight train to try and stop it before it crashes into other city bound trains. On the train they find the passengers gassed and a crude bomb device barring their way to the train driver. After disarming the device they find the train driver dead and a freight carriage missing. Leon finds that a thermal device is missing from the manifest and Lawson knows that Kronin is behind the train hijack and vows to bring him and his compound to heel much to Kerry's disgust.
A former drug user helps Tactical Response arrest a gang, however an hostage situation breakouts after the former drug users boyfriend breaks up with him, meanwhile, Kerry discovers her son James, has a drug problem. Meanwhile, Josh is injured when being pursued by a hired assassin.
On Shannon's first day as a Sergeant, her confidence is hurt after a juvenile delinquent steals the TR02 vehicle, however while pursing the criminal, she discovers he is easily avoidable. Tragedy strikes and Stella discovers she's pregnant.
The team pull over a speeding car to discover that the driver has had his penis severed and his enraged partner has gone on the run and so they must negotiate with her for the safe return before time runs out where it is no longer viable. Elsewhere, Audrey finds out that Michael slept with Stella just after he finds out that she had a miscarriage. Meanwhile, Lawson discovers Kerry at a drug supply house scoring drugs for her son.
A Cyber hacker manages to take down communications, businesses and banks across the city, bringing Josh and Tash together as they race against time to save the life of a badly injured woman. As the attack becomes more lethal, Leon and Audrey put their wits together to stop the faceless hacker.
Lawson's nemesis Andrew Kronin escapes from a police van on his way to court & the TR team take off in hot pursuit but Michael finds the ordeal tough. Meanwhile, Shannon gets ribbed for lack of a sex life.
Most of the members of TR go to the bush for a routine training exercise. Unknown to Lawson and Josh however, they soon find themselves at the mercy of Oliver Ginsberg, who has rigged the forest with deadly traps. When they discover that Ginsberg is on his way back to the city with a van full of explosives, they realize the worst is yet to come.
TR heads back to the city in search of Oliver Ginsberg and to find the bomb before he detonates it. Lawson is surprised to find that his former colleague Dom is now with the bomb squad and has to work side by side with him as an erratic Ginsberg threatens to blow the headquarters of the insurance company who sued him years previously.
TR1 give their unique farewell to Dom but Lawson doesn't participate until Stella sets him straight. Kerry's son James goes on the run after he double-crosses drug-runners bringing smack in from Vietnam and it is up to Kerry and TR1 to find him before the drug-runners do. Meanwhile, Shannon and Michael buy a house together and Leon and Audrey bond over a Russian pen-pal correspondence.
TR1 get involved in an intervention order as they take away the baby of teenager Elizabeth Heinz. But her vengeful and dangerous brothers take matters into their own hands and launch an attack against TR1 killing a young constable and endangering Audrey and Leon's lives back at base. Meanwhile, Audrey begins to see that Michael isn't the one for her and gives Leon a second chance.
Christian is taken hostage at an army barracks during a siege after he, Lawson and Shannon bring back to MP's after a street brawl. Audrey asks Michael for a reference as she has applied for the Churchill Foundation to go abroad to study with the FBI.
T.R. reluctantly team up with a covert security team to track the whereabouts of a wealthy Chinese businessman and Lawson becomes jealous when the team leader of the unit tries to woo Shannon away from T.R. and join his team. Finally, back at Shannon & Michael's investment property, Shannon and Lawson succumb to their mutual passion unknown to them that Michael has recording equipment in place to trap any burglars. Elsewhere, Audrey hears that she hasn't got on the Churchhill Fellowship and is very disappointed.
Josh's proposal to Tash is interrupted when ESD storm Tash's house and arrest him. Facing charges of corruption, Josh realises that his arrest is closely linked to the earlier attempt on his life, as he strives to clear his name once and for all.