The episode begins and as the gang prepares for Barney and Robin's wedding, they're wrapping up other things. Ted is putting the finishing touches on his house and it's not going well. Barney and Robin are rehearsing for their first dance. Lily and Marshall are packing for their year in Italy. Marshall's mom calls and Lily spills the beans about the move to Rome. Marshall's mom demands that she see Marvin before they leave. Marshall winds up offering to leave Lily in New York for work while he takes Marvin to Minnesota. Lily is outraged that Marshall is taking her infant son away from her for a full week.
Next she is seeing slamming a beer at the bar with Ted. He tells her his work on the house is done and she wants to see it, but he realizes it's only because Marshall already turned off the cable. Barney and Robin are out to dinner to relax and celebrate the fact that they have finished their wedding planning. They get a table near the window and reminisce about the time they looked out and saw two homeless people fighting over a sandwich, but it turned out they were just making love, over a sandwich. Barney has brought cigars, but an annoying couple next to them at the bar, are bothered by the mere presence of the cigars. They're Robin and Barney's new nemeses. The annoying couple even gets the table by the window because they complain about having one in the corner.
The woman's name is pronounced "Krirsten," which she annoyingly informs the hostess when they're seated. Marshall calls Lily from Minnesota, and he reports that his mother Judy isn't going to let them leave. Judy says it's not a joke. Ted shows Lily his house and she's impressed until she sees a "House for Sale" sign. He tells her he's selling the house because he's moving to Chicago. At the restaurant, Robin starts plotting what to do to the annoying couple. Barney has discovered that the guy is checking out the hostess. They're conjuring up a plan to break up Krirsten and her guy. Ted explains to Lily that Chicago is the perfect town for him. He says that she and Marshall are moving to Rome, anyway, but she reminds him that's only for a year.
When they get back, they're expecting him to be there and living in the house with his wife-to-be. Lily now tries to convince Ted that this woman exists. He doesn't believe it. Marshall calls and reports that Judy is now making jokes about moving with them to Rome. Robin comes back to the table and tells Barney that a plan is in motion and it can't be reversed. Then they watch as a server brings two glasses of champagne, one of which has an engagement ring in it (Robin shows Barney she planted her own). Krirsten is excited even though it's the wrong diamond cut for her and her guy is shocked, saying it's a mistake and they've only been together seven years. They end up fighting, while Barney and Robin toast. Ted tells Lily he's leaving the day after the wedding.
She asks him why he's in such a rush, but she realizes he's leaving not because the love of his life isn't in New York but because she is and she's married to his best friend. Marshall calls again and assures Lily that nothing is going to screw up their plan. They end their call and Marshall's phone rings. It's someone from the New York State Judiciary Committee offering him a job as a judge. The job would start a week from Tuesday and Marshall's request to have it start a year from Tuesday is denied. Marshall goes through every conceivable alternative, all of which are denied. He finally asks if there's any way he can do the job while also being in Italy for the next year, and the answer is no. A flustered Marshall says this is a big decision.
He then concedes that he’s not very good at making big decisions. Smoking their cigars, Robin and Barney are ecstatic about having broken up that seven-year relationship. But the couple shows up and tells them that they got in a big fight, called their therapist and have decided to get married. Ted tells Lily about the moment in the rain at Central Park, when Robin held his hand after he helped her find her locket. He says that if there was any way he could make the locket appear, he would. Lily confesses she knows where the locket is. She tells Ted about a day back in 2008 when he was getting ready to marry Stella and Robin was drunk at the bar wondering why Ted wasn't going to marry her instead.
Robin said she knew she should be happy for him, but she was moving to Japan just to get away from Ted. She drunkenly took Lily to Central Park and dug up the locket her "something old". They brought it back to the apartment and Robin said she was going to take it with her to Japan. Lily put it away in a pencil box, which Robin planned to take to Japan. Ted realizes that the race-car pencil box didn't go to Japan. It's sitting on his desk. He's excited, saying this is going to be the best wedding gift ever. Lily warns him to "be careful". Now, 56 hours before the wedding, Ted picks up a wrapped red box that was next to the race-car pencil box in his now-empty apartment. Barney and Robin are now rushing off to go get married.
Marshall is at the airport in Minnesota, preparing to leave, and she reminds him that in a few days they'll be in Italy. Marshall's brother overhears this and asks if Lily knows about the judgeship. Marshall concedes he hasn’t told her yet. Ted and Lily get ready to drive to the wedding and he asks her not to tell anybody about Chicago. He's leaving early on Monday. He's going to come back to the city on Sunday night. He's going to take the train. Ted's wife-to-be's boot-clad footsteps are shown at the train station, heading for Farhampton with a guitar case and a yellow umbrella in hand. Finally, at long last her face is shown. She buys one ticket for Farhampton. The season ends at this point.