End of the 20th century. A group of scientists executes a project aiming to prevent a nuclear war with the planet Khalom. From their experimental project, involving manipulating events in the past, two mysterious human creatures travel between the present and the 19th century, and back - getting in love with four different persons.

At the age of 71, a highly regarded writer, José Cardoso Pires, suffers a major stroke and loses his memory and the ability to relate to the rest of the world. Everybody seems to defy the famous author to write another novel that recounts this adventure telling his "last story", the most conclusive of his career, the one of his accidental journey to the clear shadows territory.