Reese and Finch race to save a hotel maid's life but find themselves surrounded by more suspects than they may be able to eliminate when they realize any guest or staff member could be her potential killer. Meanwhile, Detective Carter weighs a major offer from the FBI.

After The Machine gives Reese and Finch six numbers at once, their search for clues leads them to a coastal town where they are forced to ride out a storm with a group of locals in a police station. However, as the weather rages outside, a sinister situation arises inside when they realize there is an unidentified killer hiding among them.