Michael Roark

Maggie and Meredith disagree with Derek about the best way to approach a patient's case, which leads to a bigger argument between the couple. Meanwhile, Callie feels responsible when one of her veterans is pushed too far and one doctor's routine procedure results in a devastating diagnosis, on the winter finale.

Vincent and Cat are prepared to make the final sacrifice to halt an attack and eliminate beast makers from the world once and for all.

The gang draws closer together when Vincent and Cat discover another nemesis out to get Vincent; Cat and Vincent's relationship suffers when they find themselves on opposite sides of the law.

Vincent and Cat must rethink how to take down the people hunting beasts; Cat hopes no one at work discovers her ulterior motives.

Vincent reaches his breaking point when he's secretly interrogated about an impending attack causing a huge setback for Cat and Vincent.

While threats of a beast hunt and a DHS manhunt loom, Vincent and Cat try to restore some normalcy to their lives.