The prestigious Tactical Response team fills the gap between general police and special operations duties, responding to violent incidents like carjackings, suicides, and armed offences.
Josh and Dom try to rescue a woman tied to an explosive device, and Shannon helps Lawson deal with a disgruntled salesman who has trapped his boss inside a car.
When a group of students are lured to be drug mules, Tactical Response races to stop them, as Kerry warns Lawson he risks compromising a Federal investigation.
Lawson finds a young boy involved in a domestic violence situation, while Michael becomes a hero and Shannon deals with a prostitute.
An escalating hostage situation causes trouble for Shannon, and Lawson's attempts to catch a serial killer are hampered by a journalist.
Dom and Stella are caught in a prison siege when they are called to Edgehurst Prison to negotiate with Martin Gero, while Kerry struggles to deal with an accident.
A disturbance helps the team in an investigation into a series of robberies and, struggling to deal with repercussions of the cyclist's death, Kerry leads Leon on a wild night out.
Two teenagers hoping for internet notoriety blow up a series of parking pay stations, and Kerry rings Boyd while on leave at a Melbourne hotel, wanting to talk things over with him.
The Tactical Response Unit ventures into the Bush to retrieve an abducted boy - only to discover the child does not want to be rescued, and will shoot anyone who tries.
Stella's future in TR is threatened when she becomes involved in an illegal car race, while Kerry faces the inquest into the cyclist she accidentally hit.
TR responds to a suspicious car tailing an armoured van and Michael puts his life in danger when he goes against protocol taking on a group of robbers single-handedly.
Josh is caught in the middle of an ex-SAS soldier and a Major Crime investigation, while Lawson tries to protect Jacinta when a story she's investigating puts her life in danger.
Lawson races to find the kidnappers of a baby before the child's grandfather - a known criminal figure - gets to them first, and a man threatens to jump from an apartment building.
When a taxi driver assaults Shannon after she refuses to pay, Josh struggles to control his anger and the team links the incident to a spate of attacks on female passengers.
Lawson extracts an undercover agent from a drug syndicate - but matters become complicated when he discovers she is pregnant by a known criminal.
Lawson, Shannon and Stella race to save the lives of college students when two teenagers go on a rampage, while Josh realises he is attracted to Shannon at his anger management class.
Stella is caught in the crossfire when an informant is removed from witness protection against his will, while Michael delivers a baby and finds himself a changed man.
Josh and Michael clash when dealing with a delusional man who thinks he's a drug squad detective, and the team intercepts a call from a woman intent on killing her husband.
Lawson finds out about Josh's relationship with Shannon, causing the pair to come to blows, while TR tracks an escaped criminal who Josh believes has been wrongly imprisoned.
Lawson tries to stop a teenager embarking on a life of crime - only to find it is too late, while Dom struggles to deal with Sandrine's depression when it threatens to harm their baby.
A discussion about Kerry's birthday leads to a bet on who in the team will have sex with her, and Leon is caught stealing during his investigation of video store burglaries.
A bus hijack turns deadly when Lawson is forced to make a fatal decision, and the team helps remove girls from a community where reports of inappropriate behaviour have been made.
Melbourne's water is contaminated by a woman who believes fluoride in the supply killed her husband, while Stella clashes with the team as they wait for the ballistics report.