In the midst of a Parisian heatwave, Tristan, campaign manager for a candidate during the legislative elections, receives an anonymous letter containing a positive pregnancy test. Because he may have an incurable hereditary disease, Tristan become obsessed with the idea of finding the woman who sent him the test. But is he dealing with a morbid joke, a cold revenge, a cry for help, or a political ploy? Tristan decides to investigate, risking his professional and emotional life.