When the owner of a local gym is cooked alive in his sauna, Laura and team delve into the world of fitness freaks and crossfit commandos and soon realize the threat is bigger than they could have imagined.

As Laura and the team investigate who exposed an undercover cop and caused his murder, an unseen attacker breaches their systems and targets them, forcing the 2nd Precinct to switch tactics in order to find him before he gets another officer killed.