As a teenager, Catherine "Cat" Chandler witnessed the murder of her mother. Her life was spared when someone--or something--saved her from the attackers. Years later, Cat works an NYPD police officer investigating a case that leads her to the person who saved her life: a doctor named Vincent Keller. Vincent's longtime friend, J.T. Forbes, helps Vincent hide out and protects his dark secret--when enraged, he transforms into a terrifying beast, unable to control his inedible strength. Even after learning the truth, Cat is touched by the man that lives inside the beast and decides to keep her relationship with Vincent a secret from her boss, Joe Bishop, her partner, Tess Vargas, and even from her close friend, medical examiner Evan Marks. Though drawn to each other, Cat and Vincent realize that their attraction is dangerous for both of them.moreless
After the mysterious death of a rising young ballerina, Vincent suspects that the understudy, Victoria, may be withholding information about the murder. Cat and Tess learn that the victim tried to file a police report for an assault before she died. Meanwhile, Cat turns to Vincent for help in deciphering a medical paper found in her mother's belongings, and J.T. starts to worry that Cat's visits to the warehouse loft leave Vincent vulnerable to discovery by Muirfield's agents. Catherine pushes Vincent to help her learn more about the Muirfield project, but when Vincent refuses, Cat proceeds on her own, until a virus wipes her computer clean. Tess starts dating again, but quickly finds out that she's unknowingly involved with a married man. Cat's sister, Heather, moves out of Cat's apartment as she becomes more uncomfortable with Cat's quest for more answers about their mother's death.moreless
A Bosnian immigrant named Iris, is arrested on suspicion of killing the judge for deporting her brother. Vincent is convinced that Iris is innocent, and Cat works to dig up the truth. However, Cat is put on leave when her actions disrupt the official investigation. Nevertheless, Cat continues her own investigation and learns Iris is hiding a family secret, and Cat turns to Vincent for help. J.T. worries that Murifield will learn that Vincent is alive if he continues to help Cat, so Cat devises a method to communicate with Vincent without seeking him out.moreless
Vincent saves a teenage boy and takes him to the hospital, where he remains unconscious in a coma. The boy's x-rays show signs of abuse, so Cat and Tess question the boy's father, Zachary Holt, who hypothesizes that his son's ADHD and track record of fighting and gambling may have gotten him into trouble. Cat and Tess then question Lois Whitworth, who owns the Westchester Polo Club where the boy worked. They learn that Lois's daughter, Clarissa, has been going out with the victim. Though Clarissa says that she ended the relationship when she learned about her boyfriend's illegal activities, Cat and Tess suspect that she's not telling them everything. Meanwhile, Silverfox and the Murifield agents make contact with Cat and offer to tell her the truth about her mother's death if she turns over Vincent.moreless
Vincent stops a robber in a convenience store, but his safety is put in jeopardy when security cameras record his image. Things get worse when he photo shows up in the newspaper the following day. Cat and Tess work on the case of a missing woman named Amy who mysteriously disappeared after her fiancée, Dr. Michael Walters, surprised Amy by printing their engagement announcement in the newspaper the morning she disappeared. Evan uses Amy's fingerprints to learn her true identity, and Cat starts to suspect that Amy may have intentionally disappeared after Vincent tells her that that he and JT have an escape plan to abandon their loft in a matter of minutes. Later, Amy's fiancée also goes missing and Joe learns that someone hasn't been honest with his team.moreless
After Vincent appears to stand up Catherine for dinner, she wonders if Vincent may have seen her kissing Evan at her birthday party. However, Vincent actually blacked out on his way to Catherine's apartment, and he is now searching for the cause of his mysterious blackouts. A case puts Catherine and Tess in the middle of the high-class world of the SoHo art scene. Vincent is forced to admit that he has feeling for Catherine when he sees her dressed up to attend a gallery opening with Evan. At the same time, Evan makes it clear that he, too, has feelings for Catherine, leaving her to choose between two very different men.moreless
JT worries that Vincent may be implicated in Cat's murder investigation after she mentions that a local college frat brother was brutally killed. JT examines Vincent, hoping to understand the cause of his blackouts, but Vincent starts to to transform into the beast, forcing JT to tranquilize him. Meanwhile, Evan and his new intern notice an unusual cut on the victim's ankle, which looks very similar to a cut that Evan found on a female cadaver left on campus a year earlier. As Evan tries to piece together more clues from the crime scene, someone kidnaps him, and Cat turns to Vincent to track down Evan and save his life. However, she doesn't realize that she's risking Vincent's life by asking for his help.moreless
J.T. thinks that Catherine's presence has been causing Vincent's blackouts. Hoping to prove J.T. wrong, Vincent has J.T. inject him with endorphins and sedatives that trigger a fugue state. In flashback, Vincent sees his time in Afghanistan when he received his first dose of the medication and remembers the doctor who injected him with the DNA-altering substance. Vincent also recalls how the other soldiers suffered from unpredictable side effects, including fugue states, and is relieved to know that Cat isn't triggering his blackouts. Vincent tells Catherine about his memories about Murifield, and she remembers a few pieces of information. As Cat and Tennis investigate the attempted shooting of a teen pop star, Evan starts to suspects that Cat is protecting the vigilante who saved him in the subway.moreless
With Catherine's father's wedding quickly approaching, his fiancee and the bridesmaids try to find Catherine a date for the wedding. Not wanting to be set up, Cat feels pressured to admit that she's seeing somebody and reveals to Vincent that she wishes he could be her date for the wedding. At the wedding, Cat learns some startling news about a research grant that Evan received to study the mutant DNA cells that have been turning up at local crime scenes. After Cat tells Vincent about Evan's theory of how the cells are evolving to become more animal-like and less human, she faces an unexpected detour that could change the course of their relationship. Meanwhile, Tess and Joe cross the line romantically, even though Joe is married.moreless
Vincent narrowly escapes being caught by his former fiancée, Alex, and has to face the fallout of his past. While Cat recovers in the hospital, she deals with her feelings for Vincent. Meanwhile, J.T. receives an unexpected visit from someone interested in his past research on mutant DNA.
Vincent struggles to sort out his feelings for Cat and the memories from his old life with Alex. After J.T. discovers that Evan is planning to recommend that NYPD form a task force to catch the beast, he tries to figure out how to stop Evan. Meanwhile, Tess works on a case involving the mysterious skydiving death of the wife of a billionaire adventurer, while Cat remains off-duty as she recuperates from her gunshot wound.moreless
Cat starts to believe that Muirfield might have tracked down Vincent, and despite her promise to avoid seeing him, Cat has to interrupt his romantic cabin getaway with Alex to protect them. Meanwhile, Evan finds a bug in his lab, which makes him start to believe J.T.'s warnings about the dangers of his research.moreless
Cat and Vincent wonder if Alex can be trusted to keep the secret of Vincent's past. Evan discovers that Claire, the woman he is dating, has been keeping secrets from him. Heather meets Joe's younger brother, Darius, and develops feelings for him. Vincent tries to win over Cat with romantic gestures for Valentine's Day.moreless
After Cat invites Vincent to a dinner at her apartment to meet Heather and things don't go as planned, Tess and Heather stage an intervention to confront Cat about Vincent. Evan is offered a proposition that could impact his cross species investigation. Heather sneaks off with Darius at an event for Joe, leaving Vincent with a tough decision to save Heather's life.moreless
New Assistant District Attorney Gabe Lowan shows up at the precinct and immediately starts asking questions to understand why cases involving the vigilante have been mishandled. Cat continues doing everything she can to protect Vincent by any means necessary, and she tracks down a witness and threatens him at a gala masquerade ball. Meanwhile, Vincent is concerned that he might lose control and hurt Cat if they get romantically involved.moreless
Cat and Vincent must deal with the fact that someone is trying to frame the vigilante. Evan thinks he can prove that Cat knows more than she is telling. With Muirfield and the police very close to discovering Vincent' s location, Cat and J.T. must figure out a way to save him. Tess' discovery will change her dynamics with Cat.moreless
To protect Vincent, Cat must let Tess in on the secrets she's been hiding. While ADA Lowen is skeptical of the people in the department, Evan's opinion of Cat will change completely and steel his determination to find the beast.
Evan finally tells Cat her loves her but also reveals he's the one who lead Muirfield to Vincent. Gabe uncovers evidence that someone in the department was feeding information to the vigilante.
Gave reveals to Cat that he knows about Muirfield. Vincent is immediately suspicious of Gabe's intentions, but this causes tension with Cat, who wants to trust Gabe. Vincent and J.T. find new living accommodations.
Vincent turns jealous when Cat asks Gabe to join her at the family's annual tribute to her mother. Later Cat learns her mother might be alive. Vincent determines Gabe has a link to the sniper who shot the mayor at a public event.
A date in public backfires on Cat and Vincent. Cat learns something from Gabe that gives her hope in finding a cure for Vincent.
Secrets revealed will change what Cat knows about her past. Vincent faces his downfall while Gabe goes to extreme lengths to find answers.