This is the case that will make Detective Antoinette Conway's murder squad career. Or break it...

There's the murder squad you set your sights on, back at the beginning of your career: the one where you spend your day playing knife-edge mind-games with psychopathic geniuses, knowing that one wrong blink could mean the difference between victory and another dead body.

And there's the one you actually work on, when you're the squad pariah. The night shifts. The vicious jabs and the pranks that go too far. Processing scumbags and matching witness statements, sifting the dregs for the case that might get you closer to where you want to be.

Tonight's case isn't it. Uniforms call it in as a slam-dunk domestic. Except when Conway takes a good look at the victim's face, she realises she's seen her somewhere before. And suddenly the conviction that there's a different answer takes her breath away.

This is the case she imagined. Precision-cut and savage, lithe and momentous. But you can beat one killer. Beating your own squad is a whole other thing.