When an elderly gambler's number comes up, Reese and Finch head to Atlantic City to delve beneath the surface of their POI's seemingly ordinary life for answers. In New York, Carter's crusade to clear a fellow detective's name brings her perilously close to discovering the remaining HR faction within the department.

When a luminary in the world of medicine is poisoned, Reese and Finch have just 24 hours to determine the deadly toxin he was given and find the person behind the attack. Meanwhile, Detective Fusco's past corruption catches up with him when an informant gives the Internal Affairs Bureau the crucial information they need to send him to prison.