When people start spontaneously turning hard as stone with no real connection between victims, Nathan, Duke, and Lexie find themselves in a race against time to find the troubled person responsible.
The Strategic Response Unit is called when a mother and daughter are abducted, and the only clue they have about the culprit could expose a dark family secret.
The team searches for an escaped convict.
Lexa's suspicions lead the team to unveil a traveling death camp posing as a circus for mutant refugees.
On the trail of the Red Flag leader who ordered their assassination, the team discover a woman who cannot speak, but understands every known language.