The Secret, by Robert Enrico, features Jean-Louis Trintignant as an escapee from a police psychiatric ward. He has killed a guard during his escape, and makes for the country to hide in the mountains. There he comes across Thomas, a writer, and his wife Julia, who are themselves escaping from city life in Paris. They look after him and Thomas begins to believe his story that he had been tortured because he had learned a State secret. The sudden appearance of a helicopter gives credibility to his story, even though an invasion by soldiers turns out to be a military manoeuvre.

The couple decide to take the stranger to Spain, and their journey leads to a tragic conclusion. Julia kills the man, fearing that he is mad, or an espionage agent. And then the special police appear.