Originally titled "Paradox" and directed by Robert Zemeckis, "Back to the Future Part II" picks up exactly where the original ended. Marty McFly (Michael J. Fox) is kissing his high-school sweetheart, Jennifer (Elisabeth Shue replacing Claudia Wells), when out of the blue arrives the crazed, wild-haired inventor Doc Brown (Christopher Lloyd) in his time-travelling DeLorean. Brown has seen the future and it is not pretty, and warns Marty that there is a problem involving his future kids! And so they speed off into the year 2015 to the same picture-postcard town of Hill Valley. There are flying cars that leave from ramps, a theatre showing "Jaws 19," cafes that play Michael Jackson's "Beat It," hoverboards and so on (and plenty of advertising, including the Roger Rabbit doll from Zemeckis's own "Roger Rabbit" movie). Marty makes a mistake and buys a sports almanac that has scores from the years 1950 to 2000. And who else but good old Biff Tannen (Thomas F. Wilson), the bully from the original film, happens to be eavesdropping on Marty and Doc's conversations about rupturing the space time continuum and making money on predicting future game scores. Needless to say, after Marty's kids are saved from a ludicrously contrived mini-disaster, Marty and Doc head back to 1985 and find that it is a very different place. It turns out that Marty's house is not his own, his father, George, is dead, and the town is presided by a seething, evil billionaire none other than Biff himself who is married to Marty's mother! Yep, this is a cold, ugly world not unlike the alternate reality depicted in "It's A Wonderful Life."

For those who have not seen "Part II," it would be unfair to reveal much more except that this is one of those rare sequels that manages to revisit the original film. It does so in clever ways and the paradoxes and breaks in space time continuum contribute to an ingenious if rather headache-inducing screenplay. You'll need a road map to keep track of all the characters and time lines, and even then it is still confusing. As much fun as it is to make sense of all the contradicting paradoxes in the film, "Back to the Future Part II" desperately lacks joy or at least some sense of human involvement that we should feel in an adventure of this kind. It is often amusing but also repetitive and hollow - we learn plenty about Marty's family but there is never any true insight into his character. The same can be said of Doc Brown, a scientist trying to make sense of the universe and alternate timelines they occupy but there is not a whisper of much else in him - he is simply mad but comically mad, in the Jim Carrey vein.

The character of Marty's father, George (played by Jeffrey Wisseman, not Crispin Glover), is basically a cipher who floats around upside down (done on purpose presumably so we wouldn't notice that it isn't Glover). But what of his death in the alternate 1985 by the evil Biff? And what about Marty's mother, Lorraine (Lea Thompson), who in the alternate 1985 looks more haggard and drunk than in the 1985 that the original "Back to the Future" began with (I hope this is making sense). Yes, we learn about their possible futures but, again, they ring hollow at best. They are like Norman Rockwell caricatures from the 1950's that have been demonized by outside forces, namely Marty and Doc.

The first time I saw this movie, I greeted it with groans as did the audience. Seeing it a couple of times since, "Back to the Future Part II" has an addictive mentality - director Zemeckis and co-writer Bob Gale keep your interest because you have no clue where their ideas will lead you and you want to keep revisiting to make some sense of the plot. It is a frenzied, hyperkinetic nightmare of a movie, an assault on our senses that places its paradoxes and mind-bending logic on overload. But the original "Back to the Future" was a human comedy of manners, a juxtaposition of the 1950's crossed with the value system of the 1980's. The point was that the relationships were at its center and provided the heart of its story. This sequel has the same characters but insists on engaging us with paradoxes not people.