When the murder of a crooked accountant unravels a trail of greed that threatens to expose his identity as legendary assassin, Goliath, Tom and the accountant's widow, Olivia, must keep each other dangerously close. As they try to solve the riddle her husband left behind, and become more and more immersed in the puzzle of each other, Tom and Olivia draw in Tom's fellow officers DS Niamh McGovern, DCS Jackie Twomey and DC "Birdy" Bird, as well as his daughter, Izzy, until deceit and betrayal build to a shattering climax.