Lily has left for San Francisco. Ted and Robin feel the rush of budding love, but Marshall and Lily's unfulfilled love keeps them distracted. Marshall doesn't know what to do after losing Lily.
Marshall is still devastated over losing Lily. Barney tries to help Marshall meet some girls at bars, but then Barney ends up hooking up with them instead. Robin finds out that Lily is back in town, and she and Ted are torn as to whether they should tell Marshall or not. Lily instead approaches Marshall outside a bar and lets him know that she wants to get back together.
Ted parents visit New York for their anniversary and he learns a family secret. Robin worries that they won't like her. Lily and Marshall try to adjust to the new format of their relationship now that they are no longer together.
When Barney tries to prove to Ted that his job as an architect is anything but boring by showing him that it is a great way to pick up women, a jealous Robin tracks down her man after hearing of his antics, suspecting that he is cheating on her.
Lily moves in with Barney making Barney feel like he is losing his freedom and Marshall starts doing couple activities with another single guy.
Lily goes to work with Ted and steals his boss, Druthers' baseball. Barney tries to help Marshall with school by sleeping with one of his professor's.
Marshall goes out with a girl who works at the coffee shop, prompting Lily to get jealous. The group renames Barney, Swarley and torments him with the new name.
After getting back together, Lily and Marshall decide to get elope and get married in Atlantic City. They get Barney, Ted and Robin and go to Atlantic City only to find that it takes three days to get a license. They finally find someone to marry them on a boat so the laws don't apply only to decide they want to wait and have the big ceremony with the families there.
Ted is convinced that Robin's secret is that she is married. He confronts her and she tells him it's true, but then he finds out she's lying. Barney helps him find out that her real secret is that she recorded a music video about going to the mall.
When Ted, Robin, Marshall and Lily don't want to go out with Barney brings his brother for a visit, only to discover that his gay brother is getting married. Initially Barney is upset, but he comes to terms with it when he learns he's going to be an uncle.
Lily gets angry when she hears a message on the answering machine from when she and Marshall had broken up. Ted left Marshall a message calling her a "grinch." He refuses to apologize and the disagreement threatens to ruin the group's Christmas celebration. Eventually, Lily realizes Ted is a good friend and forgives him and the group goes to rescue Ted from his crazy relatives. Meanwhile, Barney has a cold and Robin takes care of him.
Robin's younger sister Katie comes for a visit. Robin tries to talk her out of losing her virginity by getting her friends to share their "first time" stories with her. But in the end it is Ted who convinces her not to do it. Meanwhile, Robin finally tells Ted she loves him and Barney makes up first time stories using movie scenes.
Barney finds a nude painting of Marshall. His friends torment him with it. Then Barney asks Lily to paint him, but is unhappy with the product. Meanwhile, Ted tries to fire his former boss, but instead ends up listening to him complain about his marital problems.
The group must go to a funeral for a man they don't even know instead of watching the Superbowl. They make a pact to not find out the winner before watching the game.
Robin and Ted miss their flight to Chicago and try to trace back the events that led up to it. It all started with a penny that Ted found, which caused him to take Robin to dinner across town.
Robin finds out that a lot of Ted's things came from his ex-girlfriends. She insists that he get rid of all of it. He finally agrees, and then finds out that her five dogs came from her ex-boyfriends.
Marshall's Fiero breaks down just before it hits the 200,000 mile mark. The group reminisces about all the great memories they have of the car. Marshall struggles with the decision whether or not to get the car fixed.
On the day Ted is moving all his stuff to Robin's, Barney tries to sabotage the move. Barney takes the truck with all Ted's stuff and Ted is forced to spend what should have been his first night living with Robin with Barney who takes him for a night on the town trying to convince him its a bad idea.
Marshall insists that he wants no strippers at his bachelor party. Barney won't listen and ruins the party by bringing a stripper. The stripper breaks her ankle forcing the guys to take her to the hospital instead of going to a boxing match.
Lily and Marshall decide to live apart for the two weeks before their wedding to prove that they are not co-dependent, but they can't do it and sneak out to meet at a hotel each night. Meanwhile, Barney is excited about his upcoming appearance on "The Price is Right" because he believes that Bob Barker is his father. He goes on the show and wins big, but doesn't tell Bob Barker that Bob is his dad, because he's afraid it might not be true.
By the time their wedding day arrives, nothing seems to be the way Marshall and Lily had envisioned. Barney saves the day by marrying them outside before the actual ceremony, so they can have the intimate outdoor wedding they dreamed of.
When Barney overhears that Ted and Robin have a secret at the wedding reception, he will not give up until he gets the secret out of them. When Ted tells him that he and Robin broke up, Barney is excited to have a single friend again. Meanwhile, Lily and Marshall are starved, because every time they try to eat someone interrupts them.