Flames engulf the car Castle was driving when he was on his way to marry the love of his life, his muse. Beckett rushes toward the inferno. Firefighters douse the flames. The driver's seat is empty. Castle is nowhere to be found. The search is on to find him. All indications are that he was run off the road and dragged from his car. The GPS on Castle's cell phone lead Beckett, Ryan and Esposito to a junkyard where the car that was chasing him is being crushed. A suspect flees, though not for long.
Beckett interrogates Gary Duffin, but the lowlife criminal isn't talking. Special Agent Connors of the FBI has been brought in to help. He believes the abduction may have something to do with revenge. If this is the case, the list of suspects is a long one.
The team learns that Duffin has ties to mob man Vinnie Cardano. Both Castle and Beckett met this guy in "Murder, He Wrote." Cardano denies having Castle grabbed, but admits that he made the car disappear for an anonymous client. Surveillance footage shows that Castle made the money drop. It appears that he was in on the abduction.
Beckett is crushed, but she refuses to believe that Castle isn't acting under duress. There's something else going on. There has to be. Beckett vows that she will find Castle. Agent Connors lets her know that she's assuming he wants to be found. Several months go by. There's still no sign of Castle until the U.S. Coast Guard finds him adrift in a small boat off the coast of Delaware.
Beckett rushes to Castle's hospital bed where he has yet to regain consciousness. She wants Lanie to take a look at him for evidence of where he's been and what happened to him. She finds a key sewn into the lining of his pants. It has the number "38" stamped on it. His blood work suggests he was exposed to a tropical virus. He was also grazed by a bullet that suggests he was shot a few weeks ago.
The Coast Guard figures Castle had been in the dingy for several days. A man named Henry Jenkins, owner of a mobile home in Massachusetts, is a new suspect in the case. He says he doesn't know Castle even though he was found in his boat in the middle of the ocean. Jenkins claims Castle had been camping on the beach. Castle's shoes and watch are found in his tent along with other supplies. There's also a bag containing his wedding tux. Once again, Beckett is crushed.
Castle awakens. He has no idea that he'd been missing for two months. Beckett is told by a doctor that he could simply be pretending he doesn't remember. Ryan and Esposito believe this is the case. Castle asks Beckett to take him to the place where the tent was found. He claims he never would have set up camp there, not after the research he did for Tropical Storm. Beckett knows he never wrote a book called Tropical Storm. Actually, he did, but threw it out. It was terrible.
Beckett questions the witness who saw Castle camping, but it's not the same Henry Jenkins from before. The first guy was an imposter. Whoever the mystery man is, he's the person at the center of what happened to Castle. Beckett admits that she lost hope a few times while he was missing. She used to have rituals that helped her get through it. Castle apologizes for everything he put Beckett through. He knows they can't just pick up where they left off. They'll get there though. They'll eventually find their way home.