Jack McEvoy has taken down killers before, but when a woman he had a one-night stand with is murdered in a particularly brutal way, he realises he might be facing a criminal mind unlike any he's ever encountered. Jack investigates against the warnings of the police and his own editor, walking a thin line between investigation and obsession, and makes a shocking discovery, connecting the crime to other mysterious deaths across the country. But then he himself becomes a suspect, and as he races to clear his name, Jack's findings point to a serial killer who uses personal data shared by the victims themselves to select and hunt his targets.