Mars Brito, a trans bike courier, is killed by an SUV. Is he the victim of an accidental 'door prize', or is this murder? His case becomes a city-wide obsession, with hourly true crime updates and rewards for clues. While this murder mystery unfolds, a Toronto trans activist (also named Mars) works with his friends on an operatic memorial, creating arias for each of the 375 trans murders that were committed around the world that year. Door Prize weaves together documentary, drama, and opera scenes into a hybrid film that explores issues of media spectacle, solidarity violence, trans visibility, and anti-trans violence.