Joshua Thane, aka Hex, is a freelance assassin. His next target is Dr Mary Wilding, a British microbiologist suspected of trading secrets. Breaking into her house, he discovers someone has beaten him to it; she's already dead. The portable hard drive he's ordered to steal is also missing. After sparing the life of her son as memories from the past trigger a crisis of conscience, Hex goes on the run to escape the wrath of his bosses after the botched job and search for the real killer. He uncovers a criminal conspiracy and a biological weapon.