A Guest + A Host = A Ghost is as free as it is associative.

Cinderella escapes at midnight, leaving behind one of her glass slippers. In the days that follow, the gay prince can't give up the idea of completing the pair.

A scientist tells us that Pluto is no longer considered a planet. The feelings of disappointment and nostalgia, and the impossibility of being able to go back to certain moments of his life, make him want to find in the story of David an answer for whatever exists beyond science and reason.

Six friends meet every evening in a basement to make music. During the daytime, however, there are no rehearsals for what life brings us. Each endeavour leaves its mark. Rita left Ricardo, Rafael found her, but she still feels lost. Eduardo thought he no longer liked Maria, but after what he has done he cannot turn the clock back. João lacks the courage to breakup with his girlfriend and takes refuge in the song he is writing for Inês. Marco struggles to get another young man’s love, but he is under no illusions. Samuel believes in everlasting love but something is wrong because his friends haven’t heard from him for sometime. Inês, attempting to feel safe, likes to experiment and she's waiting to see how things go with João. With all this going on, how could the band not be falling apart...?

The film tells the story of a sister and a brother, Inês and Rafael. Since the divorce of their parents, their family never saw Rafael again. Inês runs away from home looking for him when she is told he is back at the Guincho Beach and surfing again. Rafael is an ex-surf champion who everyday gets himself inside the most dangerous waves to test the limits of his life. When the two brothers meet, Guincho makes them come together in a promise of paradise on earth, as it was the last place where their family lived together and in happiness. But Inês is surprised one day when she finds her brother looking fixedly to the Serra de Sintra mountain range, where the Convent of the Capuchos, which once was his refuge, is. She fears having brought him back the memories of the separation of their parents. Rafael is in a crisis of faith. When one day he disappears, Inês knows he went back to the convent, and she starts doing what she can to bring him back to her.