The teenage girl was the first victim.

Her throat trim to the bone, she didn’t stand a chance. Her mother, at least, had time to fight. Briefly.

Called to the crime scene in leafy Wimbledon, Maeve Kerrigan’s first thought is that this is definitely a domestic dispute eliminated bad. But the husband is found lying bleeding and unconscious in an upstairs space. As a criminal barrister he insists he’s the third victim rather than their prime suspect, even if he’s a guy who makes foes easily.

The only other surviving family member is fifteen-year-old Lydia. She was the main one to discover her mother and twin sister’s bodies – as well as the only witness Maeve provides. But she isn’t talking…