On a country road, six-year-old Joanna Mason is the only survivor of a knife attack that leaves her mother and two siblings dead. Thirty years later, after boarding the wrong train in Yorkshire, Brodie is almost killed when the train crashes. He's saved by 16-year-old Regina Reggie Chase, the nanny of Dr. Joanna Hunter, nee Mason. In the chaos following the crash, Brodie ends up with the wallet of Andrew Decker, the recently released man convicted of murdering the Mason family. Enter DCI Louise Monroe, Brodie's former love interest, who's tracking Decker because of a recent case involving a similar family and crime. When Dr. Hunter disappears, Reggie is convinced she's been kidnapped and enlists the reluctant Brodie to track her down.