When an armed robbery at a convenience store reveals that cop killer Corey Baxter is back in Sydney, Detective Grace Gibbs has the chance to finally catch her colleague's murderer. But as she begins to track Baxter, her short fuse is tested when she's assigned a junior detective to train: Charlie Fung, who holds a deep-seated grudge against Grace.

After Mani confesses to murdering Tony Hodge, his boss at the convenience store, Grace and Charlie pinpoint holes in his story and begin to suspect he may be covering for someone. A surprising discovery at Mani's residence makes it clear that one of the students at the group house is leading a secret life. Meanwhile, new forensic evidence draws a connection to the Corey Baxter case.

The detectives delve into Bo-Lin's life and realize she may be caught up in a dangerous crime syndicate, while her boyfriend, Mani, takes matters into his own hands. As Grace and Charlie close in on Tony's killer, Corey Baxter torments his new prisoner.

Grace and Charlie come to blows over which course to take in their investigation, as Grace begins to question the evidence against Corey Baxter. With tension between them at an all-time high, the pair defy their orders and follow their instincts, hoping to catch the killer who has eluded them for so long.