How can you Trust someone with a stone cold heart?DC Cat Kinsella first meets Joseph Madden when he asks for advice about his wife, Rosa, who he says has been threatening him, although he refuses to discuss why. Dismissing it as a marriage on the rocks, Cat tells him that there's not much the police can do without firm evidence of harassment. When Joseph is arrested for the murder of Naomi Petrovic, his defence is that his wife is setting him up. Naomi was at a party attended by the couple and hosted by Rosa's best friend and sister-in-law, Kirstie Connor. A woman who is described as being 'close' to Joseph. Appearing genuinely outraged at her husband's arrest, Rosa insists that he is innocent. Cat is appointed informal Family Liaison Officer to the Madden's so she can build a profile of the couple and try to decide who is lying. When key pieces of evidence against Joseph start to look shaky, Cat begins to consider that he might be telling the truth. But why would Rosa frame her husband? What could he possibly have done that was so bad he has to be set up for murder? And who, then, killed Naomi Petrovic? The truth is never simple. Who would you believe?