Vincent is captured on a convenience store surveillance video while preventing a robbery, and Cat warns him to be extra careful when his photo appears in the newspaper. Cat and Tess investigate the disappearance of a woman named Amy (guest star Annie Murphy), who has gone missing after her fiancee, Dr. Michael Walters (guest star Jeremy Glazer), surprised his bride-to-be by placing their engagement announcement in the paper that morning. Evan runs Amy's fingerprints and discovers her true identity, while Cat wonders if her disappearance was intentional after Vincent mentions that he and JT have an escape plan to clear out of their loft without a trace in a matter of minutes. Later, Michael also goes missing and Joe learns that his team has been deceived. Meanwhile, Heather is planning a surprise birthday party for her sister, forcing Cat to postpone her birthday plans with Vincent. At the party, Cat and Evan share a surprising moment.

Vincent helps Cat investigate the suspicious death of a ballerina. Meanwhile, Tess makes a surprising discovery about the man she's dating.

A homicide detective teams with a man who takes on incredible but uncontrollable strength when enraged. In the series opener, the two meet for what they discover isn't the first time.

Vincent revives a 19-year old boy who was left for dead in a dumpster and rushes him to the E.R., where he remains in a coma. After Evan declares that the boy's x-rays reveal a history of bone fractures, Cat and Tess question the father, Zachary Holt, who worries that his son's ADHD and history of fighting and gambling might have gotten him mixed up with the wrong crowd. The detectives question Lois Whitworth, who owns the Westchester Polo Club where the boy worked. Lois is surprised to learn that her daughter, Clarissa has been dating this young man. Clarissa claims that she ended the relationship because he was involved in illegal activities, but Cat and Tess suspect that there's more to her story. Meanwhile, Silverfox and his Murifield agents track down Cat, and offer to tell her the truth about her mother in exchange for turning over Vincent, who they insist is a monster. Cat tells Vincent about her Silverfox encounter, and Vincent realizes that Cat might be afraid of him. JT wants them to flee, but Vincent refuses to leave Cat, instead offering to surrender to Silverfox in exchange for Cat's safety.

New Assistant District Attorney Gabe Lowan arrives at the precinct, suspicious that cases involving the vigilante are being mishandled, and wanting answers. Cat is determined to protect Vincent at any cost, which includes tracking down a witness and threatening him at a gala masquerade ball. Meanwhile, Vincent worries he may lose control if he gets romantically involved with Cat.

Cat is placed on leave after interfering in a murder investigation. Meanwhile, J.T. fears that Vincent will become exposed.

When Catherine’s dad gets remarried, the bride-to-be and her bridesmaids try to find the daughter-of-the-groom a date for the wedding. Uncomfortable with being set up, Cat reluctantly admits that she’s seeing somebody and confides to Vincent that she wishes he could be her date. At the wedding reception, Cat learns about a research grant that Evan received to study the mutant DNA cells found at local crime scenes. When she tells Vincent about Evan’s theory of how the cells are changing to become more animal-like and less human, she encounters an unexpected detour that could change the course of their relationship. Meanwhile, Tess and Joe cross the line romantically despite the fact that Joe is a married man.

Gabe comes clean to Cat that he knows about Muirfield. Vincent does not think Cat should trust Gabe and is suspicious of his intentions, which causes tension between them. Meanwhile, JT and Vincent finally find a new place to live.

On the anniversary of her mother's death, Cat asks Gabe to attend her family's annual remembrance of Vanessa, which makes Vincent incredibly jealous. Cat learns some information that makes her think her mom might still be alive and when a sniper shoots the mayor at a public event, Vincent finds evidence that links Gabe to the sniper.

As Cat and Vincent hunt for a black market buyer searching for beasts, they have to protect an heiress whose identity was exposed. Cat and Vincent realize how much they have to lose if Vincent's true identity is revealed.

After she's seemingly stood up by Vincent, Cat wonders if it's because he saw her kissing Evan at her birthday. Actually, Vincent mysteriously blacked out on his way to meet Cat, and is now searching for answers. Cat's case pulls her into the sophisticated world of the SoHo art scene. When Vincent finds Cat all dressed up to go to a gallery opening -- with Evan -- he has to admit that his feelings for her are growing deeper. All the while Evan makes his affections for Cat known, leaving Cat torn between the two very different suitors.

JT suspects that Catherine is the trigger of Vincent’s blackouts, so to disprove this theory, Vincent allows JT to inject him with endorphins and sedatives that force him into a fugue state. In flashback, Vincent recalls his time in Afghanistan when he received his first super soldier shot, and remembers who injected him with the DNA altering substance. He also recollects how the other soldiers experienced unpredictable side effects, including fugue states, and is relieved to know that Cat isn’t causing his blackouts. Vincent shares his memory about Murifield with Cat, who experiences some recollections of her own. Then, as Cat and Tess investigate the attempted murder of a teen pop star, Evan suspects that Cat is deliberately protecting the vigilante who saved him in the subway.

Vincent barely escapes being caught by his former fiancée, Alex and must deal with the repercussions of his past. While Cat is in the hospital, she is forced to confront her feelings for Vincent. Meanwhile, J.T. gets a surprising visitor asking about old research he did on mutant DNA.

Cat is forced to reveal things that she had been keeping from Tess to salvage their relationship, and to protect Vincent. Gabe is suspicious of everyone in the department, while Evan witnesses Cat doing something that changes his opinion of her, making him even more determined to track down the beast.

While attempting to be normal newlyweds, Cat and Vincent grapple with how to overcome the danger lurking. They find themselves in the fight of their lives when their happiness becomes jeopardized.

While working to uncover who is after Vincent, Cat discovers she might be pregnant. A lead Vincent follows puts his life in jeopardy. Meanwhile, J.T. gets kidnapped in a case of mistaken identity.

With Vincent in hiding and Cat's job on the line, they must re-group about how to bring down the people hunting beasts. Vincent tries to infiltrate a private army, while Cat scrambles to obtain information and hopes that no one at work discovers her ulterior motives.

Vincent and Cat fight to reclaim some normalcy to their lives, even as the threats of a beast bounty and a DHS manhunt loom. Meanwhile, Tess takes a huge risk by protecting Vincent from a nosy reporter.

Vincent is forced to undergo a series of tests orchestrated by the mystery buyer in order to keep from being exposed. Cat, JT and Heather work to exonerate Vincent.

Vincent is torn between his new feelings for Cat and his old memories with Alex (Bridget Regan). J.T. learns that Evan is planning to propose a task force to catch the beast and must figure out how to stop him. Meanwhile, Tess investigates the mysterious skydiving death of the wife of a billionaire adventurer, while Cat remains off duty until she recovers from being shot.

After a dinner where Cat introduces Vincent to Heather ends badly, Heather enlists Tess to stage an intervention with Cat. Evan receives an interesting proposition that could change the course of his cross species investigation and at an event to honor Joe, Heather goes missing and Vincent is forced to make a tough decision that saves her life.

Vincent and Cat decide to elope in order to draw out a superhuman assassin chasing them. J.T. tries to find a lead on the experiments, and Heather tries to focus at her new job.

After a force more powerful than anything they have ever encountered ruined Cat and Vincent’s big day, Cat becomes convinced they are in over their heads and begins to doubt their ability to stop the threat, forcing Vincent, JT, Tess and Heather to band together in hopes of convincing Cat of her greater purpose.

When Cat and Vincent make it their mission to capture Liam, they find information about a Patient X that they might be able to use to help them find him. Meanwhile, JT and Tess work to confirm that JT is serum free.

Vincent and Cat’s wedded bliss comes to a halt when they learn from J.T. that someone is trying to expose the identities of beasts. While on the hunt to find out who is behind the threat, Tess is reluctant to help since they are all trying to move forward with an attempt at normal lives.