Joel (Paul Rudd) and Molly (Amy Poehler) are on a double date with their friends Kyle (Bill Hader) and Karen (Ellie Kemper). After Kyle tells them a story about how he and Karen disagree on the Sunday paper, they ask Joel and Molly how they met. They describe their relationship as something like a romantic comedy. Joel is the typical leading man that is attractive without being threatening, and Molly is a quirky and klutzy woman. Their relationship, as most romantic comedies do, begins in New York City.
Joel was originally living with his girlfriend Tiffany (Cobie Smulders), who never really seemed to love him the way he loved her. He works at a candy conglomerate called CSR while Molly owns a struggling candy store called Upper Sweet Side that she runs with her friend Wanda (Teyonnah Paris). Joel goes to work and plays catch in the office with his buddy Bob (Jason Mantzoukas), until Joel throws the ball far enough the Bob falls through the window and hangs on for dear life. Then enters Joel's rival Trevor (Michael Ian Black), who wants to take a particular account from Joel and hints that he's going to go to Joel's apartment and have sex with Tiffany. The bigger problem is that Joel's boss, Roland (Christopher Meloni) wants to open a super CSR store right across the street from Molly's store. She consults her accountant, Eggbert (Ed Helms), who assures her that her store is indeed failing. He also unsuccessfully tries to ask Molly out.
While playing basketball with his friends, Joel plays around with the thought of asking Tiffany to marry him. All his friends have varying opinions. The perpetually single Tommy (Ken Marino) thinks marriage is a stupid idea and that the entire point of relationships is to get laid, while the happily married Teddy (Kenan Thompson) think Joel should go for it. The poetic Oliver (Jack McBrayer) also has his choice words about love. Convinced, Joel runs home to try and propose to Tiffany, even as she is loudly having sex in the bathroom with Trevor. Only until Joel turns around does he see what is going on. He leaves the apartment, heartbroken, then goes to stay with his younger, underachieving brother Jake (Max Greenfield).
Molly is invited to a Halloween party by her friend Brenda (Melanie Lynskey), who is also Bob's girlfriend, so that means he invites Joel so that they can set him and Molly up. By pure coincidence, both Joel and Molly dress up as Benjamin Franklin and bump into each other on the street. They both argue about it and end up walking together to the same apartment for the party. Brenda thinks they already know each other and that they came together (title drop!). Both Joel and Molly spend the entire party sulking, yet they do feel a mutual attraction toward one another. Joel tells Brenda and Bob that even though he could probably see himself with Molly, he thinks she's a terrible person. He turns around and sees her, and she leaves with her feelings hurt.
A while later, Molly is with Wanda at her favorite book store when she sees Joel again with Jake. Wanda and Jake leave to avoid the awkwardness. Joel says he is looking for a fiction book for his bubbe. Molly instantly feels a spark due to a shared interest in fiction books. She then invites Joel out for a coffee, where she asks for an oddly specific muffin order. When he remembers the order verbatim, Molly falls deeper in love with him. On their date, Joel admits that he's wanted to open up his own coffee shop, "Cup of Joel" (he tries to awkwardly explain the lame pun). Molly even brings him to her place to meet her sister Katherine (Zandy Hartig) and son Tucker (Skylar Gaertner), who likes Joel due to his Pokemon knowledge. However, Joel can't make the next move because he's still not over Tiffany.
With help from Jake, Joel tries to come up with an apology for Molly. She sees him outside the candy store, but she says she looks like a chimney sweep (because she's dressed like one). She and Wanda go through the rom-com "dress-up" montage, not noticing Joel entering the store, so he leaves and Molly misses him. He later calls her and invites her out to dinner. Afterwards, they go back to her place and have sex. From there, the two of them become a couple and are seen partaking in romantic activities, such as playing football with Joel hitting Molly in the face, and burying a dead person under a pile of leaves. This is all set to a Norah Jones song, complete with its own music video and cameos from Adam Scott and John Stamos.
Molly invites Joel to meet her parents. Her mother puts Joel through a test in which she attempts to seduce him, but he turns her down because he loves Molly. During dinner, Joel learns that Molly's parents are white supremacists, which totally puts him off. They argue, and they break up.
Joel goes back home to find Tiffany in his apartment, feeling vulnerable because Trevor left her and she is just using Joel to fall back on. He doesn't care, and they have crazy sex. Meanwhile, Molly decides to go out with Eggbert. She and Joel keep running into each other at Bob and Brenda's holiday parties, up until New Year's Eve when Eggbert proposes to Molly, and she accepts. After the party, Joel breaks up with Tiffany. She says she was faking it the whole time. Joel thinks she means her orgasms, but she pulls off her face to reveal that she was really Judge Judy in disguise. She says her orgasms were real and tells Joel to get his shit together.
Months pass, and although Joel tries to move on, he can't get over Molly. He pays his bubbe a visit, and as she tries to tell a story about a bagel, he quickly assumes that she is trying to create a metaphor for his life, inspiring him to go and get back the account he's been trying to get at work. But first he makes gross comments about wanting to have sex with bubbe before leaving.
Joel goes to work during a board meeting, where he stands up and inspires his co-workers and Roland to not bother with opening a new store so that Molly's can stay in business. Roland is inspired, so much that he fires Trevor and gives Joel the account he's been wanting. However, Joel quits so that he can pursue his coffee shop dreams, as well as getting back with Molly.
Jake, having found work as a cabbie, drives Joel to Molly's wedding. At the wedding, Molly gets cold feet and runs away. Joel arrives at the wedding too late, but then thinks where to look for Molly. He gets the whole wedding party to follow him to Boston, but Molly is nowhere to be found. Then they go to Brooklyn Promenade, where Molly is looking out at the ocean. Joel tries to win Molly back, but he's interrupted by her ex, Frank (Jeffrey Dean Morgan). He wants Molly back also, but she turns him down, and he walks away without a fight. Then Katherine comes running in with Tucker to tell Molly that her ex-husband Spike (Michael Shannon) just got out of prison and found out about Joel and wants to kill him. Spike comes in swinging a bat, but Joel effortlessly beats him up. Spike is taken away by cops and then shot in the face by one of the officers. Joel proposes to Molly, but she says they should take it slow and just go out for coffee. A year later, they end up getting married, and Joel opens up his coffee shop...which is really just a table outside Molly's store where he brews generic coffee.
Back in the restaurant, Joel and Molly finished telling their story, when Kyle asks, "So why did you guys decide to get a divorce?" Joel and Molly reveal that both their businesses went under, and even though Tucker was happy to have a new dad, he was traumatized to see his real dad get shot in the face. The subsequent increasing debts led Molly to become addicted to pills and she started sleeping with Frank again. Still, she and Joel mutually decided they should be friends. Kyle, inspired by his friends, tells Karen that they should break up. She nervously asks if he's joking, and he laughs, saying he was joking. Joel and Molly then contemplate giving it another shot before agreeing they should. Joel then turns around and says into the camera, "I told you it was gonna be a crazy day."
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