After a brief stint in the mayor's office, DC Cat Kinsella is back at the London Metropolitan Police, wisecracking with her partner, Luigi Parnell, and trying to avoid the wrath of the boss, Detective Inspector Kate Steele. But for Cat and Parnell, it's serious business when a young Australian woman turns up dead after a party thrown by her new employer. The initial investigation of Naomi Lockhart's murder points to Joseph Madden, whose coffee shop sits around the corner from police headquarters. Joseph insists he's innocent, that he was home with his wife, Rachel, at the time of the murder. But when the police question her, Rachel contradicts his alibi, swearing she was home alone. While the team builds its case against Joseph, Cat is tasked with getting to the heart of the Maddens' marriage. Cat knows one of them is lying, but the question of which one and why is far more complicated than she expected. As she tries to balance the demands of the investigation with a budding romance and unresolved family drama, Cat has to decide how far she'll go to keep her own past mistakes buried.