The Machine is affected by a virus that causes it to put out erratic numbers. Meanwhile, the team look for an elusive tech millionaire; and Det. Carter works to bring down Cal Beecher’s killer, but her mission has unintended consequences.
A medical luminary is poisoned, and Finch and Reese must work quickly to determine the toxin’s origin and find the attacker. Elsewhere, an informant gives the Internal Affairs Bureau pertinent information on Det. Fusco.
As Finch and Reese try to protect six people simultaneously, clues lead them to a coastal town; when a storm forces Finch and Reese to seek shelter in a police station with a group of locals, they realize a killer may be in their midst.