How I Met Your Mother: Season 4

Ted and Stella get engaged, but Ted soon learns that he doesn't know anything about her. Meanwhile, Barney confesses to Lily that he's in love with Robin.

Marshall claims that he had the best hamburger in the world during his first week in New York City, but he forgot where the burger joint is located. The gang then hits the streets of Manhattan to help him find it.

Ted invites the gang to Stella's house in New Jersey. Stella shocks him by announcing that she wants to live there permanently once they marry.

When Ted is packing his stuff for his move to New Jersey, he discovers that the gang was going to hold an intervention for his engagement to Stella and demands they hold it anyway.

Ted and Stella make the decision to get married in three days. So when the day comes, it turns out to not be all they had imagined because of the presence of their exes.

When Ted unexpectedly runs into someone from his past whom he would rather forget, the gang starts wondering how they would handle it, if it happened to them.

Lily and Marshall receive different views on whether they should have a baby. When Lily asks, Ted and Marshall turn to Robin for advice. Barney creates his own holiday for single men.

A depressed Robin joins a group of overindulging single party girls known as the "Woo Girls." Meanwhile, Barney receives a submission for design of the new company headquarters from Ted.

Ted walks into his apartment to find Robin's date sitting naked on his couch. He learns about a technique that could revolutionize dating for the whole group, and everyone thinks about whether or not they should try it out that night.

Ted tries to prove to the gang that he's not a loser after being left at the altar. Meanwhile, Barney and Ted decide to pick a fight with the guys sitting in their favorite booth to impress Robin. Robin gets turned on by the fighting.

Ted tries to keep his irresponsible sister from hooking up with Barney during her trip to New York, and Robin starts hanging out with Marshall at a bar for Minnesotans, not telling them that she's really Canadian.

When Ted and Robin decide to be "friends with benefits" to end conflicts around the apartment, Barney tries to fix their problems so they will stop sleeping with each other.

Lily comes back from a trip to Seattle only to run into a blizzard, which may threaten an airport ritual of meeting Marshall. Meanwhile, Ted & Barney offer to keep watch over the bar at MacLaren's while awaiting their dates, since Carl wants to close up early.

Robin discovers she must find employment within seven days or be deported back to Canada, and agrees to create a video resume with Barney's help.

The gang suspect Barney has a girlfriend after he suddenly leaves MacLaren's but realizes he has a wife and a son.

When Lily and Marshall get wind of the fact that Ted's college girlfriend Karen (Laura Prepon), who they always hated, has moved to New York, they try to persuade him not to contact her.

When Karen comes across another woman's earring in Ted's bed, he learns that Lily put it there on purpose. Ted discovers this isn't the first time she's covertly meddled in his relationships.

As a means of protecting Ted from discovering he has lost an important job, Marshall and Barney dream up an elaborate lie.

When Barney learns Ted has a list of things he thinks the gang is too old to do, he sets out to do every task within 24 hours in order to prove Ted wrong.

When Ted loses his job and decides to form his own architectural firm out of his apartment, he hires an intern to help get his company off the ground, but the intern gets too close for comfort with some of Ted's friends. Meanwhile, Marshall tries to make himself more valuable at work with a gimmick.

When Ted breaks Barney and Marshall's "three-days rule" by having a "text" relationship with a girl he just met, they play a cruel joke on him by pretending to be her.

Ted explains to his future children how important it is to be in the right place at the right time. Meanwhile, Barney celebrates his 200th conquest.

Tony, Stella's fiancé, makes an attempt to ease the burden he feels for "ruining Ted's life," by helping him find a job. Meanwhile, Barney wants to prove that he can get out of a speeding ticket.

Ted is trying to keep his architecture firm afloat by working all night, but Marshall tries to lure him to the roof for a surprise 31st birthday party. Robin finally learns about Barney's secret feelings for her.