Law & Order: UK

Ronnie's new partner, Joe, arrives keen and fresh from child protection, just as Ronnie, Jake, and Kate are trying to nail drug overlord Horgan for the third time. Horgan's underworld power makes him almost impossible to convict, despite Jake's best efforts, and Ronnie doesn't want to be sidetracked by training a new boy: especially as another body, hands and teeth hacked off, has just been found.

Investigating the stabbing of a psychiatrist, Ronnie and Joe are disturbed to find a secret room in his office-with a bed in it. Their concern for his underage patients, however, can't distract them from finding the killer, who is potentially dangerous and armed with a large hunting knife. Meanwhile, Jake and Kate disagree over the best charge to bring against the accused.

Tensions run high within the police force when the skeleton of a missing police officer is found 20 years after his disappearance. Friendships and loyalties are tested, and careers are put on the line, as the investigation begins to reveal corruption at the highest levels of policing. Jake and Kate face the unenviable task of putting the law itself in the witness box.

No one is more surprised than Ronnie when the course of a murder investigation leads him to the door of his old boss: Natalie Chandler. Ronnie tries not to let his history with Chandler cloud his judgment, but when pushed, how far will he go to help his friend? Jake and Kate are sympathetic, but their hands are tied-a man has died, and someone must take responsibility for it.

Everyone is on edge after an apparent suicide begins to look more sinister, and Ronnie's terrorism alarm starts to ring. Things aren't much better over at the Crown Prosecution Service, where one of Jake and Kate's professional disagreements leads to her taking matters into her own hands and risking her career in the process.

Forensics from a blood‐spattered hotel room lead Ronnie and Joe to a surprising class of criminal. It's up to Jake to prove that the wealthy and privileged are not above the law, but when an old nemesis turns up as defense counsel, can he keep his cool?

A shocking series of shootings means that Ronnie and Joe have to catch the killer before he, or she, can strike again-and the next target is one of their own. In a case where nobody is safe, Kate must hold her nerve to see that justice is done.

After a fatal stabbing in a crowded London market, the pressure is on to make Londoners feel safe again. But with Ronnie's efficacy as a detective being questioned at every turn, is it the end of the road for his career?