Siri (Matilda Källström) and David (Simon Lööf) are a young Swedish couple living together in London who have been in a committed relationship since high school. During a rainy night out at a bar, they meet Camille (Alma Jodorowsky), a French art student. In a moment of spontaneous intoxication and curiosity, the three engage in a consensual threesome. In the aftermath, Siri is consumed by unspoken jealousy, insecurity, and boundary anxiety, causing a rift between her and David. As their communication breaks down, Siri seeks comfort and emotional validation by initiating a secretive, separate affair with John (Lucien Laviscount), putting her long-term relationship with David to the ultimate test.