When a calculating killer begins marking his victims with black crosses and red roses, a relentless detective and an ambitious television reporter join forces to stop him, only to discover that the murders are the opening phase of a far larger experiment designed to teach an entire city to obey.

A young woman is murdered on a deserted city street, her killer leaving a black cross drawn across her forehead before vanishing. She is not the first. Detective Mark Rourke investigates a growing series of killings connected by black crosses and red roses, crimes that are precise, controlled and escalating, as if the killer is studying how everyone around him responds.

Television reporter Mara Kline is covering the killings when the murderer makes her part of the story: anonymous calls arrive, he references her broadcasts, and he tells her directly that she sees patterns. Mark takes her into protective custody, and the two form a wary alliance.

As the killer tests police response times, media reaction and public fear, rules begin spreading through the city with no clear origin: stay inside, turn off the lights, don’t call the police, wait, be quiet, obey. And the more Mark and Mara fight back, the better the experiment works.