Carmen Sanchez is a tough Homeland Security agent who plays by the rules. But when her sister is attacked, revealing a connection to a series of murders across Southern California, she realizes that a conventional investigation will not be enough to stop the ruthless perpetrator. With nowhere else to turn, Sanchez enlists the aid of Professor Jake Heron, a brilliant and quirky private security expert who believes rules are merely suggestions. The two have a troubled past, but he owes her a favor. They team up to catch the assailant, who has no discernible motive and fits no classic criminal profile. All they have to go on is a distinctive tattoo and a singular obsession that gives this chillingly efficient tactician his nickname: Spider. Over the next 72 hours, Sanchez and Heron find themselves in the midst of a lethal chess match with the killer as they race to stop the carnage.