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. Catherine needs to unravel the reasons behind Vincent's change if she has any hopes of recovering their epic love, while also trying to solve the secrets that swirl around her own life.
While attempting to learn more about Vincent's mission, Cat gets kidnapped by Vincent. Their growing chemistry complicates his mission. Meanwhile, Tess, J.T. and Gabe come together to help Cat.
Catherine and Vincent track a mysterious beast while keeping their individual agendas from one another in a clever game of cat-and-mouse. Meanwhile, Heather has a bombshell revelation for Cat, and Tess confronts Gabe about his real motives for helping Cat.
After getting stonewalled by Cat in his quest to track down a suspected beast, Gabe enlists Vincent's help, but Vincent quickly takes matters into his own hands. Unfortunately, the beast as an advantage over Vincent that requires Cat's help, in addition to the help of someone else who opens up old wounds from Vincent's past.
Cat gets a blast from the past as she attends her high school reunion, where she uncovers more of her past than she ever anticipated. Meanwhile, Vincent meets up with one of his old military buddies who is hiding a very dangerous secret.
Cat confronts her birth father about the mysterious role he's played in her life, while Vincent has to neutralize a high-profile beast. In the process of doing so, Vincent finds himself rescuing Tori, a damsel in distress, who may be the key to completing his mission.
After Vincent's life is endangered, Cat decides they should spend Thanksgiving with her father in order to get information on Vincent's missions. However, when Gabe and Tori join the festivities, true feelings are revealed and secrets are outed. Meanwhile, J.T. and Tess get a surprise while they celebrate Thanksgiving together.
Vincent and Cat find themselves at odds on how to deal with Agent Reynolds, which forces Vincent to wonder if he is more beast than man. Cat makes a drastic move that will forever change her relationship with Vincent.
In order to prevent Vincent from further injuries, Cat helps protect Tori when her life is threatened, revealing a new, unexpected mystery. Meanwhile, Vincent's stubborn attempt to intervene leads to life-changing consequences, which causes Gabe and Cat to grow closer.
Vincent goes on a national talk show to reveal he is still alive, while Cat dives into an undercover case for FBI Agent Dana Landon. Vincent, determined to learn more about his beastly origins, ends up coming face-to-face with Cat in the middle of a heist, which forces them to work together.
A group of criminals looking to steal a rare necklace in Tori's possession takes Cat, Tori and Tess hostage at the precinct, leaving Vincent as their only hope for help. Vincent is forced to make a decision since helping could reveal his true identity to the entire force.
Cat and Vincent must work together to save J.T. when he gets kidnapped, while Tori attempts to intervene, with fatal consequences. Meanwhile, a stranger from FBI Agent Dana Landon's past is rescued along with J.T., and might have some insight about Vincent's beastly past.
In an effort to track down Sam's captor, Vincent and Cat have to work together on Valentine's Day, which forces Cat to evaluate whether she wants to be in a relationship with Gabe.
When some of Gabe's acquaintances go missing, Cat and Vincent must come together to save them. Vincent ends up returning to the hospital where he was an intern, allowing him to see what his life could have been.
Feeling pulled between her current boyfriend and her ex, Cat has to decide between Gabe and Vincent. While Cat and Vincent work together to save Sam's latest victim, Cat's decision gets complicated when she and Vincent find themselves in a compromising situation.
In order to prevent Sam from destroying a large group of people, Cat and Vincent are forced to revisit a romantic destination from their past, which enables them to come to a new realization about what they mean to one another.
After Vincent is arrested for hug, Cat and the team must work together at all costs to clear Vincent's name. When they discover who turned Vincent in, they realize they have a bigger enemy to handle.
When Vincent becomes the subject of a city-wide manhunt, he and Cat try to stay below the radar. But they find a surprising ally when the FBI approaches them about helping on an important case.
Cat's sister Heather drops by for a surprise visit at the worst possible time, just as Gabe suspends Cat and Tess from the squad in an effort to force Vincent out of hiding.
Cat and Vincent take Agent Knox's offer to extricate and try to lead normal lives - but forces out of their control conspire to expose them and drag them back into the fray.
Desperate to start over with Cat, Gabe tries to woo her by taking her on a romantic date. However, she has plans of her own regarding how to save Vincent - while also trying to plan Heather's bachelorette party.
Cat searches for a way to thwart Gabe and finds her answer in an unexpected place: the journal of her ancestor, which makes Cat fear the only way to stop Gabe is by killing Vincent.