"WALKER," Alex Cox's retelling of William Walker's invasion of Nicaragua in the 19th century, is a perplexing fusion of cartoon and docudrama. The cartooning is joyless, the docudrama unenlightening. We aren't watching a story of Walker -- or even the obvious parable of U.S. intervention -- so much as a probing of the manic director's mind.

And that's a CAT scan most of us can do without.

"Walker" is leagues above Cox's dismal "Straight to Hell" (a misfired spaghetti western parody), but it's little more than vaguely connected sequences of murder, mayhem and absurdism (with a warm Spanish-music score by Joe Strummer): a new-wave epic with nothing epic in it. And when you consider Cox's earlier efforts ("Repo Man" and "Sid and Nancy"), where the hyperactivity was appropriate, "Walker's" failure seems more conclusive.

Based loosely on the American opportunist who proclaimed himself president of Nicaragua for two years, "Walker" is stuffed with Cox "moments": a helicopter swoops anachronistically into battle; Walker financier Cornelius Vanderbilt (played with cigar- spitting relish by Peter Boyle) is fanned by little dark boys, pharoah style; in the middle of a bloody battle, Walker (Ed Harris) plays the piano while a man lies dying, his eyeball bubbling with blood, and an English artist contemplates a painting, and so on. These scenes' shock value merely serves to make you too aware of Cox's enfant gleeful eye somewhere behind the camera.

It doesn't help that everyone plays next to, rather than in, their roles -- as though they don't want to be caught acting seriously. Ed Harris' performance gives the movie some semblance of continuity and authority -- which, ironically, is out of place against this cast of eccentric cardboard cutouts (including Marlee Matlin as Walker's mute wife). Harris twists the blockhead patriotism he gave astronaut John Glenn in "The Right Stuff" into tighter coils. This Walker values democracy "more than my own life" and declares it's the "God-given right of every American to dominate the western hemisphere." (Nudge-nudge.) He also displays a messianic sense of superiority -- on one occasion strutting ahead of his renegade soldiers of fortune as bullets whiz harmlessly past. There's something about Walker in that scene that seems to suggest Cox himself.

WALKER (R) -- At the West End.