Detective Cassie Maddox, a dynamic and intriguing character, serves as the protagonist and first-person narrator of the story. Through her, the reader not only goes inside the mind of a female detective but also goes inside the scene of the crime as Cassie assumes the identity of the murder victim. Cassie is tasked with an almost impossible mission by her former boss Frank, but for Cassie sliding into alternate identities comes naturally, and assuming the identity of Lexie Madison is easy because Cassie invented her. However, this undercover assignment is different, not only because Cassie is taking on the role of an actual person but also because Cassie is still recovering from the trauma of her last mission. Operation Vestal was a failure and left Cassie with physical and emotional wounds from which she is still healing. She lost her position on the Murder squad and her beloved partner Rob—the two had a falling out after the traumatic mission and have not spoken since. As Cassie enters Whitethorn House and the realm of the secluded group of friends, she sets out to put her failures behind her and prove herself worthy to rejoin the Dublin Murder squad.