Robin and Barney bond when they intervene in Ted's relationship, and Marshall and Lily watch a ticking clock as he fears that he soon will be the victim of food poisoning.
When Ted is faced with an important decision that might affect his future with Zoey, the gang expresses their true feelings about her.
When Marshall and Barney argue over the destruction of the Arcadian Hotel, Robin and Lily try to mix the right combination of cocktails that will force them to make up. Meanwhile, Ted plans a romantic weekend away with Zoey.
When Barney tries to bond with his father, he asks the gang to help make his life seem more exciting by lying about their own lives. Meanwhile, Robin runs into a guy she has a crush on.
Lily and Barney react badly when Marshall finally quits his job at Goliath National Bank to take a volunteer position at an environmental organization. Meanwhile, Ted and Zoey's opposing positions on the future of the Arcadia come between them.
Barney meets his father and is shocked by the differences in their lives. The rest of the gang learn their "gaps"; knowledge they should have by now, but don't.
When Barney starts to have real feelings for Nora, he worries that something is wrong with his heart. Meanwhile, Robin starts dating a guy who acts a lot like a dog.
Marshall becomes obsessed with saving the environment after seeing a documentary on garbage. Ted runs into The Captain. Barney admits he has feelings for a woman.
Barney declares February 13th a holiday for desperate women. Marshall receives a Valentine's Day surprise from Lily. Zoey and Ted work on figuring out their relationship.
Barney gets emotional when he opens up to Honey about his life. Ted admits to having feelings for Zoey to the group.
While on a trip to Minnesota, Ted and Barney try anything to make Marshall laugh. Marshall runs into an old nemesis from high school.
Afraid they will never get pregnant, Lily and Marshall decide to see a specialist. Robin begins her new job.
Lily and Marshall receive shocking news that has a profound impact on the gang. Ted begins his duties as best man for an old friend's wedding.
When Ted's new friendship with Zoey tests the theory that single men and married women can't be friends, he invites her husband, "The Captain," to hang out with them. Meanwhile, Marshall and Robin decide to spend alone time together, and Barney and Lily possibly have a fight.
When Ted leaves the bar early to prepare a Thanksgiving feast for his friends, the gang winds up partying all night with The Blitz, an old friend from college who has bad luck. As a result Ted is forced to spend Thanksgiving with Zoey.
Barney's discovery of a Canadian kids show called Space Teens, that Robin appeared on as Robin Sparkles, leads the gang to get her to reach out to her co-star, Jessica Glitter.
When the gang goes to a black tie event at the Natural History Museum, Ted gets introduced to Zoey's husband, The Captain.
When Zoey enrolls in Ted's class, she manipulates his students into taking her side in the fight to save the building being torn down to make room for his project. Meanwhile, Marshall and Lily spot Robin marching in the Halloween parade of shame.
Marshall and Lily try to figure out how to conceive a baby with the gender of their choice; Robin's perky new co-anchor irritates her.
Ted becomes conflicted after meeting an attractive woman who is passionate about saving the landmark building being torn down for his new project.
When the gang teases Robin about not being a real New Yorker, she sets out to prove them wrong by racing to catch a glimpse of Woody Allen.
Barney uses his best womanizing tactics to try to convince Ted to design the new GNB building; Robin drunk dials Don.
When Barney convinces the gang to help his mom move out of her home, they quickly learn that she has been very protective of Barney and lied to him about events throughout his life. Meanwhile, Ted gets upset when Robin oversells him to a blind date.
When Ted and Barney argue about who has "dibs" on a hot girl, Ted realizes that she is there with Cindy, a girl he previously dated who is also the roommate of his future wife. Meanwhile, Robin is heartbroken over Don, and Marshall can't keep quiet about his desire to start a family.