Bitter Christmas tells two alternating stories, one starring Elsa, an advertising director, in 2004, during a long weekend in December. The second takes place in 2026 and stars Raúl, a screenwriter and director who is writing a script that we soon discover is the story of Elsa, her boyfriend Bonifacio, and her friends Patricia and Natalia. Mixed with fiction, Elsa is, in a way, Raúl's alter ego, who, like him, resorts to autofiction as a solution to a long period of creative drought. He looks inside himself, and he can't help but also look at the people who make up his most intimate universe: his partner and his assistant. The film narrates the close relationship between reality and fiction, between inspiration and life, exploring the limits of autofiction and stories within stories.