The scene opens with Serena singing ‘Diamonds are a Girl’s Best Friend’ in just as much pomp as Marylin Monroe, but only until at the end of the dream, when Dan leaves her for Blair. When she wakes up to her stewardess’s call, she tells her she should have been awake a long time ago because the ‘lonely boy’ is arriving for breakfast buffet. Meanwhile, Blair arrives at Vera Wang for her final trial, which is when someone spyingly clicks her photograph on the way in. And there is gossip girl, who is preparing her pre-event posts for the famous blog. Dan is with Lily’s husband, and he wonders why Dan is in the wedding. He explains he did a favor for Louis, and that’s when he invited him.
Meanwhile, Chuck meets the priest over breakfast. He has the plan set up, and a new set of clothes that will allow Chuck to pass through security. The plan is to get Louis unconscious with some harmless pills, and when the priest asks for anyone who might have anything against the union, Chuck speaks out. Nothing can go wrong, because they have evidence about Blair telling the priest that she loves Chuck. So is Chuck prepared? More than the priest knows. Serena is getting down for breakfast, when Louis is overjoyed, and tells her he feels like the luckiest man in the world as Blair is marrying him. HIM! When Dan arrives, Serena has the look that suggests nothing but that she is totally in love with him.
Louis practices dancing with his mother so that he doesn’t look unimpressive. She tells him marriages are only meant to be contracts. They have nothing to do with love. If you get love, you should consider yourself lucky. And his mother likes Blair because she looks perfect to the press. She couldn’t have hoped for a more perfect arrangement. However, Louis cannot believe his mother is talking to him like this on his wedding day. His relationship with Blair is no business deal. He really loves her. Oh, all relationships are business deals, but she does hope he will be lucky enough to find love in it.
Meanwhile, Blair arrives at the venue behaving as if she is no less than a princess, and barges through the polite press-woman asking on behalf of CNN how she would like to be addressed. She would rather be with her best friend. She privately tells Serena how everything is going to change for her, and how enormous this entire event is already appearing to her. However, Serena assures her it is not that big a deal. When Blair hopes that nothing will go wrong, Serena asks what could. Meanwhile, Gossip Girl is out on a walk with her little man, and is livid to find out newspapers flashing pictures of Blair, calling her the ‘true American princess’. She is going to crash the party, but how?
Chuck announces to the priest he is not the same man who would want to spoil Blair’s happiness. If marrying Louis makes her happy, then so be it. Besides, he is not doing anything to spoil her day. And what happens to the priest? He is food poisoned on the water Chuck has imported from a toilet in Mexico. He better find public urinals with minimal queues to spend the rest of the day, and stay out of the wedding. And no, he cannot use Chuck’s toilet. When the priest bumps into Gossip Girl, she asks him to bless her – she has a feeling she is about to commit sin.
She explains her plan to the priest – those clothes he readied for Chuck are no good. She needs a nun’s dress to gatecrash. Besides, the man is always the weak link in a wedding.
Meanwhile, Blair is behaving at her adolescent best – cannot breathe in the wedding gown, doesn’t know what’s going to happen, and can hardly make sense of what her mother is saying until she gives her a tight hug – everything will be alright. She just needs to breathe. The stewardess goes for the water, and Serena for the closed windows. When Nate and Dan speak to Chuck on the phone, it turns out he is not planning to be seen at the wedding. He and his dog have a beautiful day planned ahead. And he is not the one Nate should be thinking about – Dan Humphrey is the name. That’s when Blair’s mother arrives in Chuck’s apartment. Chuck hangs up and wonders what’s happening.
After gulping the scotch left in Blair’s glass, she lets on Blair is making a mistake. She wants Chuck to marry her daughter – something she doesn’t know. Surprised, Chuck stands looking. So is he coming to interrupt the royal wedding, or not? As the guests arrive at the wedding, Blair’s mother arrives with Chuck, and leaves him in the bridal room with her. Meanwhile, Gossip Girl is preparing sabotage, as she gets ready to seduce Louis, and then have Blair catch him red-handed. However, she fails, as she unwitting mistimes her efforts. What she doesn’t fail to do is record the conversation between Chuck and Blair behind an ajar door. In it, Chuck tells her to not marry and run with him. However, she replies she loves him, more and more each day. But she cannot be with him because she promised god when she begged for his life after the accident. “He died,” so she can never be with him. She has readied herself that way. However, she wants him to know this is the hardest decision she is making in her life.
Blair leaves the room, as Chuck stands bamboozled and gradually growing disappointed, when Gossip Girl hands him the recording. Serena tells Blair she is ready to run if that’s what she wants. However, Blair wants her to tell everyone she is ready to begin. Later, Blair sends SOS – she wants both her daddies to escort her, otherwise it seems incomplete for her. Both, her mother’s ex-husband and current husband agree adorably. When the ceremony begins, and the presiding priest announces ‘let him now speak, or forever hold their peace…’ Chuck is only to be seen, but he doesn’t say a word. However, every guest in the church gets the video message in which Blair tells Chuck she loves him. Hysterical, Blair runs down the aisle, and towards Chuck. When they arrive in the anteroom, Blair is not buying that Chuck never uploaded the video. And what does he expect her to honestly believe? That he wasn’t dead?
When Serena, Dan and Nate blame Gossip Girl for sabotage, she dumps back the blame saying it could be one of them. However, Blair is getting back on the aisle, and after a public apology, she ends up marrying Prince Louis. At the after wedding dinner, which opens with an applause, Serena confesses her love to Dan.
And when the final dance is announced, Blair and Louis take to the center. As they dance, Blair is a little nervous, and overjoyed at the idea of being princess. But before long, Louis tells her why he went through with the marriage in spite of the video expose. He couldn’t not go through with it after Blair’s public apology. Louis then announces that all that stays between them now is a contract. In public, she will smile, wave and stand by him. In private, they will be nothing but strangers. Blair is shocked, but pleases her prince charming managing a smile at the cameras. Then, she scoots. She calls up someone saying she has made a big mistake, and then runs outside the event building. She waits for a car, and there comes the wedding Rolls Royce. Driving it is Dan Humphrey. Chuck arrives at the event hall wanting to apologize to Blair. Meanwhile, Gossip Girl sends in her final entries.