The gang prepares for the upcoming big wedding. Ted takes Lily to go see the renovations he's made to his house in Westchester, which turns out to be for sale, as Ted is planning on moving to Chicago after the wedding. Marshall takes baby Marvin to Minnesota one more time before the big move to Rome, but is offered the job of judge that he applied for a few months back, accepting it without Lily's permission.
Later, at the house, Lily notices the "For Sale" sign Ted left on one of the shelves, forcing him to admit that he's moving to Chicago, thinking that he can find his true love there after trying and failing so many times in New York. However, Lily correctly deduces (from that fact that Ted will leave immediately the day after the wedding) that the real reason he's moving is to run away from any lingering feelings he still harbors towards Robin. Ted then reveals that he realized that he still can't let go of Robin after he came to help her find her locket in Central Park, especially after she took the locket's loss as a sign that Barney is not the man for her, and the subsequent downpour of rain as a sign that Ted is.
It turns out, however, that Lily knows what happened to the locket: After Ted proposed to Stella, Lily found Robin drowning her sorrows at their usual booth at McLaren's. Thinking that she'll never be able to wear it on her own wedding given that the man she thought she would marry (Ted) is now engaged to someone else, Robin went to Central Park and retrieved the locket, intending to take it with her to Japan. Lily placed it in a racecar pencil box in Ted's drafting table at his apartment for safekeeping (the inebriated Robin was thinking of putting in on her butt, like her grandmother did during the War), but Robin forgot all about it before her departure. It happens, however, that Ted still had that racecar pencil box in his possession, being one of the few things he was able to save after Jeanette trashed his apartment. Ted is excited at the prospect of making Robin happy one last time before they finally part ways, but Lily remind him to be careful.
Meanwhile, Barney and Robin are enjoying each other's company at a dinner in their favorite restaurant, but inadvertently clashes with a rival couple, who annoys them by taking their favorite table near the window and telling them off from bringing out cigars. As revenge for ruining their night, Robin concocts a devious plan to break the couple apart by sending a champagne flute with an engagement ring on it (mirroring the occasion when Ted "proposed" to her by accident) to their table, to great effect. Later that evening, however, as the two were smoking cigars outside, the couple approaches them and informs them that they decided to make good of the staged proposal and are now engaged. While initially shocked that the plan backfired, Barney and Robin later felt proud and happy on helping a couple take the next step in their relationship.
On the other hand, before returning to New York, Marshall received a call from the New York judiciary, informing him that his application to become a district judge was approved. Marshall thinks about the offer, as it means that he now one step closer to achieving his dreams, but it means that he won;t be able to accompany Lily to Rome in pursuing hers.
The next morning, thirty-six hours before the wedding, the gang prepares for their departure for Farhampton: Ted moves out of his now-empty apartment, meeting with Lily along the way; he casually remarks that, since he'll be leaving for Chicago Monday morning, he'll have to take the train back to the city on Sunday night (which, of course, is where he is fated to meet the Mother). Robin and Barney are fetched by Ranjit. Marshall is driven to the airport by his brother Marcus, who asks him how he plans to tell Lily that he has accepted the offer to become a Judge. Finally, the Mother is finally shown as she buys a train ticket to Farhampton as part of the band Barney and Robin hired for their wedding.
This episode provides examples of:
- Accidental Proposal: Barney and Robin deliberately breaks up a rival couple by putting an engagement ring on a champagne glass. This backfired for the former when the latter really got engaged. Barney and Robin just congratulated them instead.
- Ass Shove: Robin, while drunk, suggested to Lily to shove, not just the locket, but also the pencil box, in her butt.
- Call-Back: Barney takes out two "El Piramide" cigars for him and Robin to share, and mentions that they were the first cigars they ever smoked together. Barney and Robin smoked these cigars in Zip, Zip, Zip, which was the first time they ever hung out together.
- I Want My Beloved to Be Happy: Ted admits that he'll still do anything just to see Robin smile. So he plans to move away immediately after her wedding.
- The Reveal: In the last moment of the season, we see the Mother's face and hear her speak for the first time.
- Wham Line: A record-breaking five of them.Lily: Just think, [Ted], this is the house your kids are going to grow up in. They are going to roast marshmallows in this fireplace. They're gonna experiment with recreational drugs on that porch. They're gonna sit on a couch right here and listen to your boring stories about— "For sale" sign? Are you selling this place?NYSJC Employer: Marshall Eriksen? I'm calling from the New York State Judiciary Committee. Uh, you applied for a judgeship a few months ago, remember?Marcus: (on Marshall telling Lily about the job offer) Good luck with that...Your Honor.Ted: I'm gonna have to head back to the city Sunday night.Lily: How will you get back?Ted: ...guess I'll take the train.The Mother: Hi. One ticket to Farhampton, please.