As Detective Dan Lockhart is called to a wealthy London street to investigate Natasha’s death, he’s startled by the similarity to a previous case. Noticing the cable-tie restraints and the tiny scratches on Natasha’s wedding finger, Dan already knows what he will find if he looks in her mouth – the metal ball which choked her to death. He knows Natasha isn’t the killer’s first victim and is certain that he will strike again.