1,001 Films: "Sherlock, Jr." (1924)

Sherlock, Jr. is Keaton at the very peak of his powers, resulting in one of the most fluid, relentlessly inventive screen comedies. Even when his projectionist-turned-amateur detective, tired of questing for recognition of his talents, falls asleep, his other/dream/imagined self remains restless, emerging from the earthly Keaton's dozing form to clamber inside a star vehicle all his own in the still-dazzling, how-did-they-do-that? film-within-a-film centrepiece.

The Surrealists (possibly up to and including David Lynch) were bound to love it - the answer to a case comes to the detective in his dreams - but Sherlock, Jr. also plays like a rumination on what we might glean from paying close attention to the movies: consider the final moments, in which the projectionist is schooled in wooing his beloved by the images unfolding on the screen in front of him. (The very last image is eloquent indeed on the general cluelessness of the male.)

It's a mix of subtleties easily missed first time round (the mirror gag later appropriated by the Zuckers for Airplane!) and set-pieces that display consummate skill, craft and flair, such as the exploding pool ball sequence, which treats comedy as sport, and is all the funnier for the sense of threat invoked - and for Keaton's deadpan excellence when faced with such a threat. All this, and a premium-grade banana-skin gag.

Sherlock, Jr. is available to rent from lovefilm.com.