Stella says yes to Ted's marriage proposal but Marshall is worried that they don't know enough about each other. He and Ted hatch a plan to put their compatiblity to the test. Meanwhile, Barney admits to Lily that he's in love with Robin and she tries to help him win her over.
Marshall takes the gang on a hunt through the city for the first burger place he ever ate at in New York with the best burgers in the city. He also accepts a job at a bank with Barney.
After inviting the gang to Stella's apartment in New Jersey, Ted tries to sell them on the perks of living in the suburbs until he learns that she expects him to move there after they're married. Meanwhile, Robin quits her job thinking that she already has another lined up. The job turns out to be an interview but she winds up with a new job as a foreign correspondent in Japan.
When Ted discovers that the gang ditched their plans to stage an intervention for his engagement to Stella, he is adamant that they go through with it anyway.
After Stella and Ted make the spontaneous decision to get married in three days, the presence of their exes destroys what was to be the "happiest day of their lives." Robin begs Ted to reconsider marrying Stella but Stella ends up running off with her ex. Barney's plan to bed Robin again is dashed by Stella's agressive sister and his own nature.
While out for dinner with the gang, Ted runs into Stella, prompting each of them to think about how they would handle bumping into someone they'd rather forget.
When Lily and Marshall contemplate making the life-changing decision to have a baby, Lily turns to Ted and Robin for advice and their very different points of view on the issue. In protest of the decision, Barney creates a new holiday for men who are not fathers.
Robin rediscovers the "Woo Girls," a group of single girls who like to go out and party. Meanwhile, Ted pitches Barney a design for his company's new headquarters.
After Ted walks into the apartment to find Robin's date sitting on the couch in the buff, the gang realizes this method might be the easiest way to get their dates into bed with them.