After six-months of sobriety, Bridget Kelly is finally starting to turn her life around when she serves as the lone witness in a murder trial. Despite the assurances of her FBI protector, Agent Victor Machado, Bridget realizes that her life is in danger. Telling no one, Bridget flees to New York, where she reunites with her estranged twin, Siobhan Martin. Wealthy, pampered, and married to the handsome Andrew Martin, Siobhan lives what appears to be the perfect life – a life in which no one is aware that Bridget exists. The sisters seem to be mending their troubled relationship until Siobhan mysteriously disappears, and Bridget decides to assume her sister's identity. Bridget discovers shocking secrets, not only about her sister and her marriage, but also about Siobhan's best friend, Gemma Butler, and Gemma's husband, Henry.