Just as 4 cell-mates are about to launch their elaborate escape from a tiny cell, a detainee from a cell-block under repair is transferred in. The 4 all face certain conviction & long sentences. Does the young new jail-mate have the same incentive & if so can they trust him. Director Jacques Becker used mainly non-actors for purposes of authenticity. In fact, one of his choices was actually involved in the 1947 escape. Becker died two weeks after completing the film. La Sante prison was replicated right down to the smallest details, thanks to the help of the three actual members of the escape whom Becker hired to serve as production consultants. Shot over a period of 10 weeks. Jean-Pierre Melville regarded this as one of the greatest French films ever made and he his right.