Premarital sex has been prohibited in the United States for three years, allowing for only one night of exemption each year. Rexton Labs, a powerful company, has introduced wrist tattoos that change color, signifying the restricted 12-hour period when intimacy is permissible. Owen, portrayed by Callum Turner, is the owner of a local pizza shop who plans to utilize the exemption night to pop the question to his girlfriend, Malika. However, his plans are thrown into disarray when he meets her at a sushi restaurant and learns of her intention to sleep with another individual in their apartment that same night.
Allie, enacted by Monica Barbaro, is an aspiring singer known for performing cover songs in commercials. She has a plan to enjoy a night out with her friend Jacinta, aiming to forge meaningful connections. Unfortunately, Jacinta quickly finds her partner and abandons Allie, leaving her feeling somewhat lost. Meanwhile, Owen finds himself lamenting his breakup at his mother Linda's apartment, played by Molly Ringwald. However, Linda informs Owen that she has plans to spend the night with her partner, Rick, prompting Owen to take his leave.
Owen's path crosses with Allie's when they briefly encounter each other outside her apartment, but things take a turn for the worse when he vomits the sushi he just consumed. Seeking solace, Owen heads to a local bar where he strikes up a conversation with a bartender who agrees to meet him after her shift ends. In his frantic quest to find a condom, he discovers that they're sold out at every store he visits.
At the same time, Allie also ventures to a bar, turning down various superficial suitors until she connects with a piano player who sings "All Out of Love" alongside her. Their destinies intertwine once more as Owen and Allie both end up at a convenience store, vying for the last condom available for an outrageous price of $200. In a moment of desperation, they team up to steal the coveted item, narrowly escaping the store owner and later retrieving it from a sewer grate. However, to Owen's dismay, Allie takes the condom for herself and leaves with her date.
In the midst of further mishaps, Owen attempts to meet a potential partner through a dating app, only to be robbed of his belongings and clothes at Brooklyn Bridge Park. Allie's date, on the other hand, takes a turn for the worse when police arrive at the apartment, arresting him for multiple counts of illicit intimacy outside the exemption period. Their fates converge again at the police station, where Owen and Allie agree to join forces in their search for partners after overhearing information about a party.
As Owen shares details about his pizza shop and Allie discusses her unique tattoo of the Little Red Lighthouse, they crash the party with newfound camaraderie. Owen successfully captures the attention of a wealthy woman named Vivian, played by Ella Loudon, while Allie meets her idol, musician Ezra Stone. During a pivotal moment, Owen encourages Allie to overcome her stage fright, leading her to sing "Only You" on stage. Ezra, however, soon exhibits behavior that turns Allie off, resulting in an unexpected hospital visit.
After dealing with Ezra, Owen brings Vivian back to his mother’s apartment, yet their moment is interrupted by Linda and Rick, causing Vivian to storm out. Feeling dejected, Allie seeks comfort and decides to visit Owen's pizza shop, where he is also retreating from the events of the night. They share a pizza, and as their feelings for each other begin to deepen, Owen receives a call from Malika, who has changed her mind and wants him to return home. Allie wrestles with the decision to keep him with her but ultimately encourages him to go back to Malika.
As dawn approaches, Owen arrives at Malika's, only to realize it was a mistake. In search of Allie, he heads to her building but cannot find her. Upon her return, Allie discovers Owen's search for her and eventually finds him at the Little Red Lighthouse. Their initial intention is to engage in intimacy during the final moments of the exemption, but they ultimately choose to wait until next year's occasion.
Fast forward one year later, Allie and Owen choose to spend the night in together as the next exemption night commences, symbolizing a shift in their relationship and their understanding of love.
