The much awaited Caskett wedding did not happen in "Castle" Season Finale, titled "For Better or For Worse." There was no fairytale ending though Castle and Beckett overcame all the obstacles, including mobs.
When Castle and Beckett go to get a marriage licence, they discover that Beckett need a divorce certificate, as she is married to a guy called Rogan O' Leary. She had got married at a wedding chapel in Las Vegas. She was drunk at the time and did not see it as a real wedding, thus did not remember it.
All the wedding arrangements are done and only three days are left for the wedding date. Beckett wants to get married on the fixed date. With the help of Esposito and Ryan, she finds Rogan's current location. Beckett takes off alone to get Rogan's signature on the mutual consent divorce paper.
Rogan agrees to sign on the paper, but there is a condition. He wants her to get onto her ex-girl's truck to get a garage door open. Beckett does that in her own way, without getting caught. However, Rogan is abducted by two masked men before he could sign the paper.
Meanwhile, Castle gets a call from the wedding venue. It is not good news. There has been a fire accident at the venue. Alexis comes-up with the idea of using their house at Hampton for the wedding.
Castle joins Beckett in her search to find Rogan so that they could get married on the date. The two go back to Rogan's house to see if they can find any clue. When they enter, they see a gang of biker-gangsters waiting for Rogan. He owes money to them, as he had hired them to steal a mobile phone from a stripper but disappeared when it came to paying. They threaten Beckett and Castle and leave after giving them 12 hours of time. Rogan's ex-girl informs Castle and Beckett that Rogan wanted a laptop, which is kept in the garage.
Lanie calls-up to inform Beckett that a pipe burst at an apartment above hers has destroyed her wedding gown. It is not wearable. Beckett is disheartened and feels that her wedding is jinxed. Castle assures her that theirs is a great love story and all such love stories have obstacles. Castle cheers Beckett up by saying that they will have a fairy-tale ending, after ups and downs.
Tory calls up to tell Castle and Beckett that there is a hidden folder in the laptop. The hidden folder contains pictures that were downloaded from the stripper's stolen phone. One of the pictures features the local pastor with the stripper. Rogan was blackmailing him. The Pastor, however, says he has no role to play in Rogan's kidnapping, and he was ready to pay Rogan.
Afterwards, Castle and Beckett find Rogan in a barn. He is tied to a chair and gagged. Beckett is not ready to free him completely till he signs the mutual consent divorce paper. Rogan tells the couple that his life is in danger, as one of the pictures is of Mickey Barbozza. Castle and Beckett recognise him as the FBI's most wanted mob hit-man who has been a fugitive for almost a decade. There is a photo of his with the stripper, and thus Rogan was abducted.
Before the trio can get out of the place, Barbozza and his men arrive. Barbozza wants his photos and Castle leads them all to Rogan's apartment. At the apartment, the biker-gangsters are waiting for their money. Beckett tells them that Barbozza is worth much more than the money Rogan has to pay them. There is a reward of $100,000 for Barbozza's capture. Rogan gets out of the trouble zone and he signs the paper.
At the wedding venue at Hampton, things are looking perfect. Beckett is looking stunning in her mother's wedding gown. Martha presents her family's heirloom, a pair of earrings. Castle calls-up to tell Beckett that he has got the marriage licence and is reaching the venue soon. He tells her that he loves her. In the mirror, he sees a black car following his car. Afterwards, Beckett gets another call.
Beckett gets out of a car and rushes to an accident spot. She breaks-down seeing Castle's car burning in a ditch. Castle is nowhere to be seen.