Giulia is constantly torn between the need to feel at home and be loved and a wild desire for freedom. One day she finds herself homeless and begins, in her own crazy way, to seek shelter and her own place in the world. Between an illusory desire for motherhood and ways to make ends meet, she spends the hottest days of a torrid Roman summer surrounded by elusive characters with empty lives, yet pure and wonderful like her. In a limbo made up of nothing (and everything), Giulia understands that it is up to her to decide how to live, or not to live, her own life.

A train station in Sicily. There are two people in the waiting room: one is “the man with the flower in his mouth” in the film's title, who has confronted and threatened a mysterious woman outside the station. The other is “the peaceful customer,” who missed his train because of presents for the women in his family which hindered him as he ran and made him trip on the train tracks. The man with the flower in his mouth has helped the peaceful customer and immediately establishes a relationship of trust and empathy with him. The two recount their lives, but whereas the peaceful man talks about his frustrations, the man with the flower in his mouth keeps steering the conversation toward just one topic: death. Everything seems wrapped in mystery, starting with the identity of the woman outside the station...