THERE'S SOMETHING immensely satisfying about "Back to the Future Part III": It's not that Doc falls in love. Or that Marty McFly gets to jump through time again in that trusty DeLorean. It's not that the action takes place in the colorful Wild West.

It's that "Future III" is the last in the series.

Knowing this creates the perfect state of mind for this final installment. You can enjoy this encore of "Future" fare with wistful eyes (if you do, please don't sit next to me), or you can view it at minimal summer-floss level, or you can just pass and let this "Future" fade into the past, not to mention the red.

Actually, as far as sequel-mongering goes, the "Future" triad is one of the least offensive, in that original creators Bob Gale and Robert Zemeckis have stayed with the project (as opposed to subleasing the directing to studio-appointed hacks) and have maintained an inventive, witty air throughout. However, the filmmaking team has called things to a halt just in time. "Future III" has its passing charms, but it also shows distinct signs of flagging.

In case you're unacquainted with the saga thus far, young Marty McFly (Michael J. Fox) and his great inventor-friend, Doc (Christopher Lloyd), have been hopping through time in their aforementioned, gull-winged automobile, stopping at the years 1955, 1985 and 2015, in order to keep things from turning out wrong in the end. In both movies, they've had to contend with the dastardly Tannen family, whose purpose has been to ensure things turn out wrong in the end.

Now, in "Future III," the McFly-Tannen rivalry returns. Marty must journey to 1885 to save Doc from the worst Tannen of all, Buford "Mad Dog" Tannen (played by all-purpose Tannen-character, Thomas F. Wilson), a lowdown ancestral varmint with a bad temper and a drooling problem.

But Doc has just met schoolteacher Mary Steenburgen, a woman who shares the inventor's passion for Jules Verne. So, there's a problem in getting the lovestruck gadgetman back to the present or the future -- or us back to the story. It often seems as though the movie cools its stirrups while Doc meets Girl.

Naturally, many of the familiar "Future" elements are there, sometimes with a little twist to them. Hill Valley, for instance, becomes a pioneer cowboy town, and the milk bar in "I," which was an Eighties-theme bar in "II," is a swing-door saloon in "III." McFly gets called "yellow-bellied" instead of "chicken." McFly and Doc have to get the DeLorean up to a time-traveling 88 mph, but in an era when gasoline has yet to be invented. As always, that launching will go right down to the wire.

Just don't expect your engine to do much more than idle.