DIAL M FOR MURDER and SPOOKS! -- At the Key in Georgetown.

Everybody knows Alfred Hitchcock's "Dial M for Murder," the 1954 murder-mystery classic in which an ethereal Grace Kelly is targeted for murder by her husband, the despicably suave Ray Milland. But what everybody doesn't know is that the film was orginally shot in that trail-blazing, short lived '50s phenomenon, 3-D. Since the fad had died out by the time the film went into release, "Dial M" has rarely been shown the way Hitchcock intended it to be. Now it is, in a revival at the Key.

Forget those flimsy red-and-green cellophane specs you wore for "Creature from the Black Lagoon." We're talking quality 3-D: gray polarized lenses in spiffy black plastic frames. Hitchcock filmed his movie in what's called the two-strip method -- "the original and the best 3-D process," says Key Theater owner David Levy.

Of course, he would say that.

The process literally adds a whole new dimension to the film. Imagine the famous murder scene; in 3-D it's doubly, or rather triply, effective. Seemingly ordinary objects -- lamps, Margot's handbag, wineglasses, wrought-iron grillwork or even puffs of smoke -- loom ominously large now as they frame the scenes.

What the movie has lost in credibility over the years, it more than gains as a period piece. Grace Kelly in her push-up bra having the most ladylike breakdown in history. Nerdy Robert Cummings. Dapper cop John Williams, foreshadowing Lt. Columbo with his "One more thing, sir. . ." Of course, it's hard to believe keychains hadn't been invented in 1954, but it's still a great movie.

The mechanics of two-strip 3-D are complicated: Two complete prints of the film run simultaneously on two projectors with special motors attached. The motors insure that each film runs at exactly the same speed, with each frame overlapping the other slightly. A silver screen is also required for optimum effect. All in all, the whole process requires "so much work you can see why it didn't catch on," Levy says. In this case, it's definitely worth the effort.

Hitchcock's restrained use of the 3-D gimmick is in marked contrast to "Spooks!," the 3-D Three Stooges short showing with the movie. This is what is usually thought of as 3-D: pies and hypo needles coming right atcha. We also get the usual Stooge antics -- they're just as revolting as you remembered they were -- plus some double entendres you probably didn't notice in the third grade. You probably also didn't notice then that the stooges were balding, sad-eyed older guys with paunches.