One of the more suspenseful films I have seen in quite a while.
Probably influenced Frank Daramont’s Shawshank Redemption
The film is based on a true event concerning five prison inmates in La Santé Prison in France in 1947. Becker, who died just weeks after shooting had wrapped, cast mostly non-actors for the main roles, including one man (Jean Keraudy) who was actually involved in the 1947 escape attempt, and who introduces the film.—Wikipedia