Three months after Vincent Keller was abducted by Muirfield, Detective Catherine Chandler is reunited with him - but not in the way she planned. He's changed: his scar has disappeared, his memory has been wiped clean and he returns as a supercharged beast on a mysterious mission.
Cat and Vincent spend the night together. Cat is called to another vigilante crime scene but when she tries to convince Joe this is not the work of the vigilante he ignores her. Muirfield contact Evan, expecting him to sabotage the forensic evidence if necessary to keep the task force from finding the vigilante so they can get to him first. Tess is angry with Joe for sidelining her from field-work and sending her instead to interview the victims of attacks that the vigilante protected. Cat and Vincent rig the lab to blow when the task force arrive but Muirfield get there beforehand and after Vincent and Cat's narrow escape Tess finds Vincent in the subterranean tunnels and shoots him.
A beautiful detective falls in love with an ex-soldier who goes into hiding from the secret government organization that turned him into a mechanically charged beast.