Two deaths, days apart but clearly linked. Each victim has had the tips of their fingers removed with a hacksaw. Reuben Maitland, freshly returned to GeneCrime, is heading up the case. The forensics come in, DNA is sampled, the clues begin to mount up. Then the killer strikes again, but not to kill. Reuben's young son is snatched. The murderer sends Reuben a message: 'Stop hunting me. Come after me and your son will die.' Reuben now faces the choice every cop dreads: the price of stopping a psychopath from killing again could be the life of his own child.