Half a year after choosing to turn her life around and embrace sobriety, Bridget becomes a witness to a murder. Fearing for her safety and skeptical of the FBI’s ability to protect her, she flees to New York to seek refuge with her affluent twin sister, Siobhan. Initially, things seem promising as the sisters mend their strained relationship, but then Siobhan mysteriously disappears. Bridget takes on her sister’s identity, only to discover that Siobhan’s life is far from ideal and just as perilous as her own.