Ted Mosby tells his kids the story how he met their mother, but he is tells it in very small bits - each week a different part of his past that inolves his best friends Marshall, Lily, Robin and Barney.
The Best Man
While Barney prepares for his wedding, he and Ted reminisce about Punchy’s wedding, which was ruined due to Marshall’s drunk antics. Robin considers telling Barney she has feelings for him until Barney receives a call from Nora.
The Naked Truth
Marshall finally lands his dream job, but he worries that his new employer would rescind the offer because of some past videos showing him as a streaker- Beercules. Meanwhile, Ted is at a loss over whom to take to the Architects’ Ball while Barney tries to convince Nora that he can be trustworthy.
Ted runs into his old girlfriend, Victoria, and tries to make amends with her since he cheated during their relationship. She reveals she’s engaged to a man she met in Germany. Marshall and Lily make a bet with Barney that could force him to wear Marshall’s ducky tie.
The Stinson Missile Crisis
Robin is forced to undergo court-mandated therapy sessions after she assaults a girl who is out to ruin Barney’s relationship with Nora. Robin becomes attracted to her therapist. Ted gets too involved in Lily’s pregnancy.
Ted takes his class on a field trip and Barney tags along. Meanwhile, Marshall takes matters into his own hands when his boss treads too carefully in making a huge settlement with a major company.
Mystery vs. History
The gang intervenes in Ted’s business when he refuses to gather information online about a woman he is going to date with disastrous consequences. Meanwhile, Marshall and Lily decide not to find out the sex of their baby, but Barney soon tempts them to change their minds while setting up the baby’s room. Kevin, Robin’s boyfriend, paints the baby’s bedroom.
Kevin helps the gang realize that their partners remind them of one of their parents, depressing and embarrassing Marshall and Lily. Meanwhile, Barney and Nora’s planned romantic evening is ruined by a string of horrible events.
The Slutty Pumpkin Returns
Ted runs into "The Slutty Pumpkin" (Katie Holmes) but realizes that she is not "The One"and actually has nothing in common with him. Barney learns he is part Canadian, to his dismay and Robin’s joy, and Lily has pregnancy brain.
While the gang reminisces about Hurricane Irene, Barney tries to cut a deal with Marshall and Lily to get out of wearing the Ducky Tie.
Tick Tick Tick…
Barney and Robin hide a deep secret from their partners after sleeping together. Barney admits that he loves Robin and breaks up with Nora. Ted, Lily and Marshall attend a concert.
The Rebound Girl
On Thanksgiving, Ted and Barney talk about a potential life-changing decision together by adopting a baby. Barney then steals a baby who turned out to be his brother’s new baby girl. Robin tries to discourage Marshall and Lily from moving to Long Island to start their new life as a family. Robin reveals a shocking secret to Barney concerning their night together.
Symphony of Illumination
Robin receives the bad news that she can never have children and decides to hide it from the gang. Marshall is trapped on the roof of his house in the suburbs and is blackmailed by a teenager to stay there.
Marshall visits his father’s grave to continue an old family tradition. Barney and Ted open a new bar and Robin’s career takes a more positive turn.
Marshall and Lily move to Long Island and her father won’t stop tormenting them about their house. Barney declares himself "New Leader of the Gang" now that Lily is not present to boss Barney around. The new and ’improved’ gang embrace the ’new Lily and Marshall’ (lily’s stripper doppelgänger and her boyfriend) with bad consequences.
The Burning Beekeeper
Lily and Marshall throw a housewarming party, where various things go awry.
The Drunk Train
Lily and Marshall invite Robin and Kevin on a Valentine’s Day trip to Vermont. Lily and Marshall worry about scores concerning the pregnancy. Kevin and Robin use the trip to talk about taking their relationship to the next level. Robin admits to Kevin that she can’t have children and he proposes. Meanwhile, Barney realizes he has finally met his match.
After Kevin breaks up with Robin, Ted confesses his feelings to her. Barney finds something private in Marshall and Lily’s things. Marshall says something to Robin that he feels Ted loves her too much to say. Special appearance by Conan O’Brien as a background extra in MacLaren’s.
Barney tries to convince Quinn, aka Karma the stripper, (Becki Newton) to go out with him. Ted wonders what to do with the room now vacated by Robin, who has moved out to the suburbs with help from Marshall and Lily.
Barney and Quinn want to move in together, but Barney’s friends do not like or trust Quinn and try to break them up. Robin and Ted fight over who deserves to sublet Quinn’s apartment.
Ted, Marshall and Barney watch the original Star Wars trilogy and suddenly think about their lives three years into the future.
Now We’re Even
Although Ted is happy with living alone at his new apartment, Barney tries to convince him about going out every night, attempting to distract himself from the disturbing thoughts of what Quinn would be doing at that moment. Lily has a naughty dream, but Marshall is not in it. Robin finally starts her stint as a news anchor at World Wide News.
Marshall panics when a baby shower indicates that the birth is close at hand and accidentally takes a road trip with Barney to Atlantic City where he gets completely and utterly drunk. Ted hallucinates seeing Robin while trying to get over her and decides to patch up their differences. Barney tries to talk Quinn out of being a stripper. Lily goes into labor.
The Magician’s Code, part 1
Marshall and Barney are still in Atlantic City when Lily goes into labor. In order to get back to Manhattan in time for the birth, Marshall must do a deal with the devil — Barney. While waiting for them to get back to the city, Ted and Robin try to keep Lily’s mind occupied with stories.
The Magician’s Code, part 2
Ted realizes that he has a history of bad relationships with every girl he has dated except for Victoria, and makes it a plan to contact her. Ted is conflicted when Victoria meets up with him on her wedding day and asks him to runaway with her. Lily and Marshall have Robin take pictures of the baby’s first day. Meanwhile, Barney and Quinn are arrested by airport security while on the way to Hawaii when Barney refuses to open a box they are travelling with. On Barney’s future wedding day, his bride is finally revealed.