When seven-year-old Lori Gilbert goes missing, Police Chief Graci pulls Detective Jess King out of the Police Call Centre—the Siberia of the Force—and puts her on the case. The Challenge: find the missing girl. The Reward: Jess gets to head up the elite Major Crimes Task Force. Jess takes command of her resistant new squad as they track down leads that are already cooling. And when their number one suspect, a sex offender on the prowl, comes up with an airtight alibi, it seems that Jess’ last chance at redemption is already slipping away…

Homicide is trying to convict two major drug traffickers, the Barrata Brothers, of murder. But when the Drug Squad nails a wise guy named DeMarco for possession, they unwittingly take Homicide's only lead off the streets. Graci hands the mess to Jess, ordering her to solve the murders and bring peace to the cop shop. At the Don Jail, Jess identifies DeMarco's unlikely confidante, a biker named T-Bone, and promises him a break on his own assault sentence if he agrees to act as an undercover agent for the police. Jess puts her trust in her volatile informant, but when T-Bone goes AWOL, he jeopardizes the case and Jess’ reputation.

When Detective Jenny Hicks refutes Amanda Jacobs’ claim that she was brutally raped by the Riverdale Rapist, Amanda sues the Police Services. Enter Jess King, ordered to investigate the Amanda Jacobs case while the Sex Crimes Unit continues to investigate the Riverdale Rapist. Jess believes Amanda and takes over both cases, to the ire of Hicks, who quits the Service. And new evidence suggests Amanda's rapist is far more sinister and much closer to home. The Major Crimes Task Force is pushed to its limits in bringing a serial predator to justice.

When Detective Eleni Demaris interrupts a home invasion in progress, she’s beaten into a coma, and Jess will stop at nothing to avenge her friend. But according to Graci, she’ll have to work with Detective Ray Arnold – a member of Toronto's notorious Robbery squad – to do it. Robbery squad members are known for their violent tendencies and sloppy work ethic, and Ray is no exception. Ray zeroes in on an ex-con with an eerily similar modus operandi, but Jess fears Ray’s tunnel vision is compromising the investigation. As victims pile up, Jess and Ray must find a way to work together to catch a ruthless criminal with nothing to lose.

Jess King is aghast when she discovers her nemesis, Seymour Keegan, a vicious serial predator, is back in town and targeting a new victim. Jess knows Seymour killed a teen girl five years ago but she didn't have enough evidence to convict. Jess tries and fails to trap her Moby Dick in a sting, but when she turns up nothing but circumstantial evidence, Graci takes Jess off the case. Or so he thinks. Jess goes rogue and tracks Seymour on her own using her team and some questionable tactics. Seymour loves the attention, and that’s when Jess makes the connection - he's a clinical narcissist and he’s taunting her. When another girl goes missing, Jess must rein in her obsession in order to save her before it's too late.

Ahmad, the bright star of the University’s Bio Chem department, was also an observant Muslim, and his violent murder has all the makings of a hate crime. But when Jess discovers Ahmad was secretly gay, the case becomes more complicated. To make matters worse, the murderer seems to delight in misleading the police, leaving Jess to wonder: is this a hate crime at all, or an elaborate cover up? Jess navigates the ambitious and cutthroat world of academia, squaring off with a brilliant sociopath who just might have committed the perfect murder.

When a video of Danny's partner, Jim Perry, beating his Confidential Informant is caught on tape and televised, Danny and Perry are suspended. Graci has Jess take over their ongoing investigation: the shooting of Scott Flanigan, an innocent bystander caught in gang crossfire at a skating rink. But when Jess discovers that Flanigan was actually the target of the shooting, the case blows open. Digging deeper to find a motive, Jess suspects the killer used the gang's notorious rivalry as a decoy for a crime of passion.

When Trevor Winter, an anti-racist activist, provokes a white supremacist group, he is beaten in his own house, which prompts Child Protection Services to take away his kids. The media makes the Police Force look bad for not making any arrests and tearing a family apart. To improve optics, Graci puts King on the case. But when Jess' prime suspect, a skinhead leader, turns out to be an undercover federal agent, Jess is stumped. New evidence emerges, and Jess discovers the true perp has a more personal motive for keeping the family apart.