15 years ago…
We see Emma and Adam sitting on a bench looking uncomfortable while other teenagers are making out. Adam cries, revealing that he's attending summer camp because his parents are going through a divorce. Emma awkwardly puts her arm around him and comforts him by saying that people just aren't meant to stay together forever. Adam seems consoled. He then asks if he can finger her. She refuses.
5 years ago…
Emma (Natalie Portman) wearing a trench coat walks into a frat party at a university in Michigan and finds her friend, Patrice. Patrice, wearing a tank top and daisy duke pajama shorts, teases Emma for wearing red long johns to the "pajama party." Across the room, Adam (Ashton Kutcher) spots Emma and tells his friend Eli that he knows her from somewhere. Emma catches his stare and recognizes him. They walk towards each other and chat. Emma invites Adam to "this thing" she has to attend the next day and Adam agrees to accompany her.
The next day we see Emma's mom; her sister, Katie; Katie's boyfriend; and Adam standing in a cemetery. Emma invited Adam to attend her dad's funeral, and Adam not knowing the occasion is underdressed. Later in the day, Adam catches Emma consoling her mother outside in the family's garden.
1 year ago…
Eli, Adam, and Vanessa (Adam's girlfriend) are at an LA farmer's market when Eli spots Patrice. They reconnect and talk. Adam walks up and hugs Patrice. Emma, who is shopping nearby with Katie, sees Adam and walks up to everyone. She is excited to see him (as is Adam) until Adam introduces her to Vanessa. Emma reveals that she just moved to LA to work as an intern at a nearby hospital. She gives Adam her phone number, and they promise to keep in touch. They don't.
Adam is working as a production's assistant for a TV show. He is a budding screenwriter; he writes an episode for the show but has yet to gain the nerves to give it to the director/producer. His dad, Alvin (Kevin Kline), is a successful film star (or producer) but Adam wants to break out on his own. While visiting Alvin at his estate, Vanessa surprises Adam wearing only a bikini. It's apparent the Alvin and Vanessa are dating. Disgusted, Adam leaves.
At the bar where Wallace, another friend, works we see Adam and Eli drinking. Adam is visibly upset. He then decides that the best course of action is to dial all the girls on his cell phone until one agrees to sleep with him. With each call, he drinks more and more until he passes out.
The next morning Adam awakens in an apartment to find himself laying on a couch with only a dish towel covering his "lap". A girl named Shira is sitting on a bar stool eating breakfast. He thinks they slept together until her roommate, Guy, walks in. Adam is unsure about what occurred the previous night. Then Patrice walks into the room, and Adam is thrilled to recognize her. She pretends that they had sex. Then Emma walks into the kitchen and tells Adam that he called her, came over, and passed out. Everyone laughs.
Adam and Emma go into her bedroom so that he can retrieve his pants. Emma reveals what happened yesterday evening: Adam, thinking he was at home, strips to his birthday suit and danced around; he also cried when telling her that Alvin and Vanessa are dating. They laugh and sit on her bed. Sparks fly, they kiss, they have sex.
Before leaving for work Emma makes Adam promise not to divulge what just happened. He agrees. Meeting Eli for lunch Adam tells his friend that he slept with Emma, but she has yet to return any of his phone calls. Just then, Emma gets out of the car with a handsome coworker, Sam. It's clear that Sam likes Emma. They chat for a bit before Emma and Sam go into the bistro to grab coffees and salads. Adam then decides to surprise Emma.
He goes to the hospital with a congratulatory balloon and they talk. Emma's embarrassed that he tracked her down, telling him that's she is not the relationship type of girl. She leaves to go back to work, and Adam, a bit sad, meets up with his friends for drinks. During the night, Emma texts Adam with, "What are you doing?". Eli and Wallace agree that she's asking for a booty call and advise him to play it cool. He does and Emma invites herself over to his house.
They meet and have sex again. Afterwards, Emma starts dressing and Adam asks her to stay for a muffin. Again, Emma declares that she's not into dating or spending the night or eating breakfast with a man. Adam agrees prompting Emma to ask, "Do you want to do this? Use each other for sex?". Adam says, "I can handle it." They agree to a few ground rules: no dating, no spending the night, no putting each other on their emergency contact list, and if one begins feeling more than the other the "relationship" but immediately terminate.
The next few weeks (or months) find Emma and Adam doing it everywhere. It's obvious they are both starting to fall for each other but are refusing to acknowledge it. In the meantime, Adam attempts to hand his screenplay to his boss. It doesn't go well, but Lucy, his boss's assistant, apprehends the play and says she'll take a look at it.
The next evening we find Emma, Patrice, and Shire sprawled out on their living room. Their periods have synced, and they're all miserable. Adam surprises the ladies with Sprinkles cupcakes, and for Emma, he gives her a period CD. She is touched. They go to her room and fall asleep. Fully clothed. The next morning Emma wakes up to find Adam spooning her and she's dismayed at herself for allowing it. She wakes him up and tells him they need to cool their situation by sleeping with other people. Adam, not amused but too chicken to confess his feelings, says fine and leaves.
That night Adam is hanging out with Wallace when Megan, another friend, confesses that she's in love with Lisa, who happens to be sitting next to Adam. The girls start making out. Wallace takes a picture of the girls kissing Adam and texts it to Emma. She's at her work party when she receives the message. Irate and very drunk, she takes a cab to his house. When Adam opens the door, she starts getting mad until Megan appears. She's wearing nothing but her underwear. Then Lisa appears, also scantily clothed. Emma is visibly upset then goes nuts on the girls, prompting them to leave. Adam and Emma have sex. And Emma tells him not to do that again. Their "relationship" continues.
A few weeks later Adam is at work when Alvin surprises him with a birthday song. The entire TV cast sings him happy birthday. Alvin invites his son to dinner because he and Vanessa have something to share. Adam, still upset at his dad, punches him, which lands him in the ER. Emma rushes to his side and finds out that she's on his emergency contact list. She tries to break it off, but Adam intercedes, telling her that he's heavily sedated and about to meet his dad and ex-girlfriend for dinner and needs a support system. He asks her to join him. She agrees.
Alvin, Vanessa, Adam and Emma are sitting in a fancy restaurant when Alvin and Vanessa tell Adam that they want to make a baby together, but before they do that, they want Adam's blessing. Adam responds by hitting his head on the table. Emma responds for him, telling off Alvin and Vanessa, saying that they shouldn’t make a baby since they're babies themselves. She lets out her true feelings for Adam indirectly by telling Vanessa that if she had to choose between Alvin and Adam she'd choose Adam every single time. Before leaving she retorts that Adam is the best sex of her life. They exit the restaurant and Adam asks her out on a real date. Emma, a bit hesitant, agrees.
It's Valentine's day, and Adam picks up Emma at work and they go miniature golfing. They talk and laugh and hit it off yet again. At the diner, they share a milkshake when Adam decides it's time to confess his feelings and begins to tell her he's falling for her. But she doesn't let him finish. At LACMA, Adam tries again and tells her that he's in love with Emma. She responds by hitting him and telling him that he's ruining their relationship. She commands him to take her back to work, and he does. At the hospital, Adam says he can't keep doing this anymore and ends their "relationship." They leave.
Six weeks pass and we find out that Emma's depressed. Meanwhile, Lucy has given the episode to their boss who decides to use it. On the night of Adam's episode, we see him basking in his success. Meanwhile, Emma is in Santa Barbara for her sister's wedding. Emma and her mom have a talk in which her mom tells her not to close up her life but instead embrace it, even if it means getting hurt when falling in love. Emma realizes she loves Adam and Katie tells her to call him. She does, and Adam who's at the cast party answers it. After hearing, Emma say she misses him he tells her that she's only saying that because she's feeling lonely since it's her sister's wedding. She'll get over it. He hangs up on her and takes Lucy home.
Emma, realizing that she has to do something big, leaves Santa Barbara and heads back to Adam's house in LA, hoping to find him there and confess her true feelings. She arrives before he does and hides out in the bushes when she realizes that he is bringing a girl home. After Adam and Lucy enter the house Emma gets into her car, calls Katie, and cries, telling her she's too late. She starts driving back to Santa Barbara when she gets a text from Shira who is working at the hospital.
While Emma is driving back to Santa Barbara, Adam and Lucy start making out, but it's apparent that they aren't in sync with each other. His phone rings and Adam picks up. The call is about Alvin, who has apparently overdosed. Adam rushes to the hospital to discover that Vanessa, who is waiting for him, wants out of the relationship. "He's too old, and I'm too young," she says. She gives an excuse why she can't see Alvin and disappears. Adam finds his dad's room, and they talk. Alvin tells Adam that while he has a selfish heart, Adam doesn't and is a good guy. Adam forgives his dad and tells him that he'll call him the next day.
While Adam walks out of the hospital, he calls Emma and tells her that she has no right to tell her she misses him when he hasn't heard from her in weeks. As he is telling her that, she has to do more than just call him her car pulls up and Emma runs out of the car. Unsure of his feelings towards him, Emma cries and tells her she is in love with him. Adam embraces Emma. They kiss.
The next morning we see them eating breakfast and discussing the new rules to their official relationship. They head back to Santa Barbara, just in time for Katie's wedding. Holding hands, the music swells and the film ends.
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