Lumet's origins as a director of teledrama may well be obvious here in his first film, but there is no denying the suitability of his style - sweaty close-ups, gritty monochrome 'realism', one-set claustrophobia - to his subject. Scripted by Reginald Rose from his own teleplay, the story is pretty contrived - during a murder trial, one man's doubts about the accused's guilt gradually overcome the rather less-than-democratic prejudices of the other eleven members of the jury - but the treatment is tense, lucid, and admirably economical. Fonda, though typecast as the bastion of liberalism, gives a nicely underplayed performance, while Cobb, Marshall and Begley in particular are highly effective in support. But what really transforms the piece from a rather talky demonstration that a man is innocent until proven guilty, is the consistently taut, sweltering atmosphere, created largely by Boris Kaufman's excellent camerawork. The result, however devoid of action, is a strangely realistic thriller.