[The Connection] is one of the rare stage pieces that is improved in its screen version.

This often means, as the junkies beadily note, nothing more than that the director has been visually flashy, eliminated the lines that can be better expressed in the cinema by the way someone shrugs or behaves when he is alone, and perhaps realised the potentialities of film to the extent of adding a car crash to the action. Shirley Clarke, the young American who made The Connection, has done something more crucial: though she adheres closely to the original text and never stirs outside the junkies' pad, she has altered the relation of the audience to what is going on, which in The Connection is peculiarly important.

In the stage version, the play hangs on the Pirandellian device of an "author" who is planted in the audience, complaining intermittently that his work...