The Bourne Identity, based on Robert Ludlum's 1980 best-seller, is a throwback thriller in more ways than one. About a merciless CIA assassin (Matt Damon) who finds himself fleeing across Europe with a serious case of amnesia and several killer colleagues on his tail, it recalls such paranoid intrigues as ''Three Days of the Condor.'' And with a hero who doesn't know why everyone's trying to kill him, it also evokes Hitchcock man-on-the-run pictures from ''The 39 Steps'' to ''North by Northwest.'' Alas, unlike those earlier films, this one never pauses long enough to explore its protagonist's psychological state or to deepen his romantic connection with his reluctant traveling companion (''Run Lola Run'''s Franka Potente). But the sleek, streamlined result has the urgency of a feature-length chase sequence.
Even while moving at a post-MTV clip, the action itself has a retro feel. The explosions aren't computer-generated, the martial arts aren't in midair, and the one car chase is more about expert stunt driving than virtuoso editing. Director Doug Liman grasps what old-schoolers like John Frankenheimer simply knew: Sometimes, even in an action flick, less is more.