Juan is a boy whose sister has been evicted by science. Despite his young age, he realizes the problem, and with the intention of finding a solution, he undertakes a long journey during which he will suffer multiple vicissitudes, adventures, and dangers. Some strange beings, who descended from a spaceship, will try to help him, but everything is useless.

Carlos Juliá
as Juan

José Nieto
as Viajante / Melchor

Antonio Machín
as Chófer / Baltasar

Antonio Molino Rojo
as Revisor / Gaspar

Carmen López Lagar
as Leñadora

María Victoria Durá
as Lucía

Carlos Otero
as Director

Glòria Roig
as Madre

Santiago Rivero
as Médico / Pastor

Montserrat Porta
as Felisa