The episode begins with Castle wondering why the girls have been taken to a different country. Al Mazri tells him that he has no clue. Gates arrives with the sketch of a man who was seen walking out of the driveway after the girls were taken. Mazri and Castle have never seen that man before. Castle wants them to do something. Harris tells him that they need to follow protocol and asks Castle to be patient. Later, Castle tells Kate that Alexis sounded very scared when she made the call. Kate tells him the best thing is that Alexis is not yet hurt. Castle and Kate are told that the kidnappers have put forth a ransom demand of 15 million Euros.
Al Mazri doesn’t want the cops to be involved. He tells them that his wife’s brother-in-law will be making the drop. Castle thanks Al Mazri. The couple leaves. Harris tells Castle that there are security cameras all over the decided spot. They watch as the exchange takes place. After Ahmed, the brother-in-law, drops the money the men drive away. They see Ahmed bring Sara to the car, and she is safe, but there is no sign of Alexis. Castle is worried. Kate tells Castle that Sara told them she and Alexis got separated and that is the last time she saw Alexis. Castle leaves to break the news to Martha and he doesn’t want Kate to come.
Kate goes to check on Castle and finds out from Martha that Castle did not come home. Martha checks Castle’s drawer and finds that his passport is missing. She realizes that Castle has gone to France to take matters in his own hands. We then see that Castle has already reached France. Kate tells Ryan and Esposito that Castle is in France. She tells them she needs to act like a cop and solve this case. She asks Esposito to circle back to the Feds and ask them to widen the search for any private jets that have flown to Europe. She is hitting a wall with Hansen and wants Ryan to check with the narcotics department for any leads on Hansen. It seems Castle knows someone in France who might help him find his daughter.
Kate tells Ryan and Esposito that they need to find Alexis before Castle does something stupid. In France, Castle meets Gaston, the adviser of the Minister of Defense and it looks like he is an old friend. He asks Gaston to help him. Gaston tells him that it will be expensive but Castle doesn’t care. Gaston asks him to stay close to his phone. Meanwhile, Esposito tells Kate that the kidnappers stole a jet for the ransom exchange. Kate feels that something doesn’t add up. Ryan tells Kate that Narcotics couldn’t help them much with Hansen, but he found out that Hansen had a girlfriend. Castle gets a text to meet someone at the church. Castle goes to the church and meets a man who takes him to someone who will analyze the call that Alexis made to him when she escaped.
The man is blind, but he tells Castle that he has a keen sense of hearing. He listens to the call and amplifies the background noises. He figures out that there is a church nearby to the building where they held Alexis and also that the building has a restaurant. They then ask Castle to take a nap because it will take them some time to find something. Meanwhile, Kate interrogates Hansen’s girlfriend and gets his address. Kate, Ryan, and Esposito then go to Hansen’s place and find that it has been tossed. She wonders why the men, who hired Hansen to kidnap the girls, would torture Hansen to death and then toss his place. She tells Esposito to talk to the neighbors. Ryan finds a computer and Kate asks him to tear it apart.
In France, the bearded man takes Castle to the place where the girls were kept, but now the place is empty. The bearded man, Henri, tells Castle that this place is too clean, which means that the men have intelligence training. He then finds a listening device on the wall and talks into the device. He tells the kidnappers that he wants the girl back safe and sound, or else he will be coming for them. He knows that they would have figured out who he is and his reputation. Just then the phone rings; it is the kidnappers and they want to talk. Henri is about to leave and Castle wants to go with him. Henri tells him that a negotiation means that Alexis is safe.
Meanwhile, Esposito brings the sketch of the guy who the neighbors saw leaving Hansen’s house the other day; it is the same guy who was seen coming out of the driveway. Henri is back and he brings Alexis’ picture. He tells him that Alexis is safe but they are demanding more money. At the precinct, the IT guy manages to pull some data from Hansen’s computer; there are surveillance photos of Alexis. This means that Alexis was the target, not Sara. Henri and Castle arrive to make the drop and Henri turns on him. He tells Castle that he would have never taken up the job if he had known who Alexis is. The masked men who get out from the car, walk towards them and take Castle with them. Henri takes the briefcase, which has the money in it. The masked men are about to shoot Castle and Castle hears a set of gun shots. He looks around and finds that everyone around him is dead, including Henri.
A man walks up to Castle and asks him to get into the car. Kate calls Castle and tells him that Alexis was the target, but the man takes away Castle’s phone and shoots it. He then asks Castle to pick up the briefcase and get into the car. Castle has a tough time trusting him, but he seems to have no option. The man tells Castle his name is Jackson Hunt, though he is obviously lying. Jackson brings Castle to a house, which has a wall covered with Alexis’ pictures.
Castle doesn’t understand what is going on. The phone rings and a man, named Volkov, tells Castle to hand the phone to Jackson. Volkov tells Jackson that he would set Alexis free, if he surrenders himself. Jackson agrees. Jackson then tells Castle that he is his father and that he is also an intelligence asset. His work does not allow him to keep in touch with his family. He tells Castle that Volkov is a feared KGB agent and that he had killed Volkov’s wife, who was counter intelligence, 12 years ago. He then had Volkov sent to the Chechen prison. Volkov managed to escape and, since then, he has been trying to draw Jackson in. Volkov found about his family and kidnapped Alexis. Jackson tells Castle that Volkov doesn’t know he found out where Alexis is being held. He tells Castle the only way to get Alexis is to break into the place and rescue her.
Castle is caught by Volkov’s men and they take away Castle’s walkie-talkie. Volkov tells Jackson that he has ten seconds to turn himself in or else he will kill Castle. Jackson tells Volkov he will not shoot Castle because he will be dead before that. The walkie-talkie in Volkov’s hand explodes. Castle then uses a watch to blow open the door of the cage, and he runs with Alexis. Jackson had told him to keep running until he reaches the US Embassy.
Alexis and Castle make it to the Embassy. We then see the scene (flashback) where Jackson is explaining the plan to Castle. Castle asks his father how he would know if he survived the plan. Jackson tells him that he will let him know, unofficially. Cut to the present, Castle and Alexis return home; Martha and Kate are delighted to see them. Castle finds a package that arrived for him in the mail, a copy of Casino Royale. This means that Jackson is alive. Castle tells his mother that he has something to tell her. The episode ends.