While Barney prepares for his wedding to a mystery bride, he and Ted reminisce about Punchy's wedding, including when Marshall and Lily announced they are having a baby. Meanwhile, Robin considers telling Barney she has feelings for him.
Marshall gets a great job offer that he fears may be scuttled by a social media background check. Ted needs a date for the Architects Ball.
Barney faces having to wear Marshall's ducky tie if he loses a bet with him. Meanwhile, Ted hopes to apologize to an ex for cheating on her.
After Robin assaults a girl who is out to ruin Barney's relationship, she is forced to begin court-mandated therapy sessions. Meanwhile, Ted gets too involved in Lily's pregnancy.
Marshall decides to step in after seeing his boss's approach to settling with a million dollar company. Ted's class trip isn't what he envisioned.
When Ted goes on a date without researching the girl on the Internet, the gang interferes, showing Kevin that they are too into each other's business. Meanwhile, Lily and Marshall come to terms with finding out the sex of their baby.
The gang begins to realize their romantic partner reminds them of one of their parents. Meanwhile, Barney and Nora's planned romantic evening is ruined by a string of bad events.
Ted finally meets his mystery girl in the Slutty Pumpkin costume. Meanwhile, Barney learns he is part Canadian, 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.
Barney and Robin are afraid to break the news to Nora and Kevin that they cheated with each other and want to get back together, while Ted and Marshall get stoned together at a concert.
Ted and Barney discuss making a life-changing decision together, and Robin tries to discourage Marshall and Lily from moving to Long Island.
Robin receives bad news and decides to hide it from the gang. Marshall hangs Christmas decorations in his house in the suburbs with some help from his neighbor.
After celebrating New Year's Eve, Marshall visits his father's graveside to carry on their tradition of tailgating. Meanwhile, Barney and Ted open a bar called "Puzzles," and Robin is forced to fill in for an inebriated news anchor.
Lily and Marshall officially move to the suburbs and realize that Lily's bossy father refuses to move out of their house. Meanwhile, the gang adjusts to them moving by going to a strip club.
Lily asks for her father's help when she and Marshall decide to throw a housewarming party. Marshall's boss gets under Ted's skin and the two nearly come to blows, and Barney puts the moves on a wacky divorcée.
Lily and Marshall invite Robin and Kevin on a Valentine's Day trip to Vermont. Kevin and Robin use the trip to talk about taking their relationship to the next level. Meanwhile, Barney realizes he has finally met his match.
When Robin breaks up with Kevin, Ted confesses his feelings to her. Meanwhile, Barney is on a mission to find something private of Marshall and Lily's.
Barney continues his pursuit of Quinn. Ted has to deal with Robin's old room, while Robin gets a taste of suburban life from Marshall and Lily.
The gang tries to break up Barney and Quinn after learning they plan on moving in together, leaving Robin and Ted to fight over who deserves to sublet her apartment.
Ted, Marshall and Barney embark on another "trilogy time", where they get together every three years to watch the "Star Wars" trilogy and envision what their lives will be like in another three years. Meanwhile Barney and Quinn move in together.
Although Ted is happy with living alone at his new apartment, Barney tries to convince him about going out every night. Lily has a naughty dream about someone other than Marshall. 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. 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.
When Lily goes into labor, Ted and Robin distract her by telling her stories while Marshall hurries back from Atlantic City.
Ted is conflicted when Victoria approaches him on her wedding day and asks him to elope. 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.
