What would you do if you took your family for a fun day at Universal Studios, watched your husband and son go on a ride and when they return... they are completely different people? For Jack Connors it's a nightmare when he tries to convince park security, police, and then hospital staff that the two people claiming to be his loved ones are impostors. Worse... he has no proof. They are far from home and the only photo in his wallet is that of the man and child from the ride. Something sinister is afoot but Jack isn't quite sure what... or why his whole world has just gone haywire.

In this sequel to the best-selling book, Haywire, Jack Connors and Sean Delaney, who've survived being hunted down by aliens, are living under assumed names in Mexico. They're finally getting over the events which sent them into hiding, but Jack is taunted by nightmares of his son, Nicky, calling out to him. Jack is traumatized as these episodes become more frequent, and he starts to worry that the secret government agency that was creating hybrid human-alien babies—of which his son, Nicky, and Sean's son, David, were part of the horrifying program—has found them. Sean tries to calm Jack, assuring him that he is just paranoid and fearful. Nobody knows who they are. But then strange things start to happen. Jack is shocked when he and Sean meet a US Marshal who claims to be on vacation in Mexico, but is he really? Is Jack losing the plot? The marshal is traveling with his wife and daughter. Can it be a coincidence…or is something terrible about to happen?