After years of assuming FBI agent Emily Byrne was a possible victim of serial killer Conrad Harlow, she is miraculously returned to her family; Emily struggles with the mysteries of her captivity an the fact that people have moved on without her.

As Emily's alleged serial killer is being released from jail, she has not come close to solving the mystery of her kidnapping and time in captivity; a witness appears and reinforces Emily's suspicions, which Emily denies.

When the witness testifying against Emily is murdered, all signs suggest that Emily committed the crime; while Tommy Gibbs and the Boston police chief are accusing Emily, she and Nick look for a FBI agent who forced the witness to lie.

The evidence against Emily is too much for the FBI and Boston PD to ignore, so they ask her to turn herself in; old feelings between Nick and Emily come to the surface; Emily decides to flee and try to solve the mystery that is ruining her life.

The hunt for Emily intensifies when one of the FBI's own agents is found dead, leading Nick to question everything about Emily and her return.

Emily returns to Boston to find that the only person who can help her may be the very one seeking to destroy her.