Six young people play a dangerous game of tag in public, chasing each other through the crowds, streets, and buildings of Chicago. This secret, one-of-a-kind, wildly expensive game offers a macabre twist to the childhood version: If you get tagged, you die.

Three "Its" have their reasons for buying a place in the game. Surgically enhanced Brandy is obsessed with destroying a naturally beautiful girl. Untalented Robert covets his target's position as superstar of the basketball team. Brainiac Charles craves a battle against an intellectual equal. Given their elite social status, they reject any possible downside to the contest. Each expects the satisfaction of killing their prey, then walking away.

Handpicked innocents play as "Runners", under threat to their loved ones should they refuse to participate: lovely, small-town Laura; celebrated athlete Tyrese; and Amanda, gamer extraordinaire. Alone, hunted by their adversary, each feels a single hope: to survive.

Technological wizardry controls the game. As soon as Runners receive the "Go" signal on smartwatches locked to their wrists, the game rockets them through the city, from the El to Michigan Avenue to the Lincoln Park Zoo. There is no time to rest. Every 30 minutes the Runner's location is transmitted, steadily diminishing the Runner's chance of ever reaching home base alive.

The game will not end until someone is tagged, so the Runners must choose how to play. Will they accept death? Will they murder their "Its"? Or will they find a way to use their individual strengths to stop the game before anyone dies?