Catherine “Cat” Chandler is a smart, no-nonsense homicide detective, who is haunted by her own tragic past. When she was a teenager, Cat witnessed the murder of her mother at the hands of two gunmen. Cat would have been killed too, but someone – or something – saved her. No one has ever believed her, but she knows it wasn’t an animal that attacked the assassins…though it was strange and terrifying, it was human. Years have passed, and although she thinks about her mother every day, Cat is now strong and confident, a capable police detective working with her equally talented partner, Tess Vargas. The two women make a good team, and have become close friends while working on countless homicide cases under the supervision of their tough-but-fair boss, Joe Bishop. Cat has also become close to another co-worker, the medical examiner Evan Marks, and they’ve developed a fun, flirtatious relationship that could easily turn into something deeper – if Cat would let that happen. However, much to the concern of her younger sister, Heather Chandler, Cat’s romantic inclinations tend toward bad boys. While investigating a new case Cat and Tess discover fingerprints that lead to a handsome doctor named Vincent Keller, who was reportedly killed by enemy fire while serving in Afghanistan in 2002. Digging deeper, Cat learns that Vincent is actually still alive. For mysterious reasons that have forced him to live outside of traditional society, Vincent has been in hiding for the past 10 years. With the help of his childhood friend J.T. Forbes, Vincent has been able to guard his terrible secret – when he is enraged, he becomes a terrifying beast, unable to control his super-strength and heightened senses. Cat is stunned when Vincent admits he was the “animal” who saved her the night of her mother’s murder. Vincent doesn’t admit the whole truth – he is emotionally tied to Cat and has been watching over her for years. Cat agrees to protect Vincent’s identity in return for any insight he may have into her mother’s murder. Thus begins a complex relationship between Cat and Vincent, who understand that their connection is extremely dangerous for both of them. Cat’s secret obsession with Vincent puts a strain on her relationship with everyone around her, and Tess is especially troubled by the feeling that Cat is keeping something from her.