A solid, old-fashioned prison movie, still a Clint Eastwood vehicle for all that it's based on fact, but refreshingly sparing on excessive violence and four-letter words.

Familiar elements of the genre - the prison gang leader, the martinet warden, the eventual break - are smoothly integrated with a downbeat approach that eschews making heroes out of the quartet of inmates bent on escape.

Director Don Siegel (credited here as Donald) is clearly having little truck with sideline issues and, indeed, with a movie already running towards two hours, he has little call for them.

His actors, Eastwood included, sink themselves entirely in their roles, and all problems are (perhaps too obviously) eased aside for the final bid for freedom.

Few of those who see the film are likely to find it below their expectations. Sharp eyes may glimpse Danny Glover in a very minor role.