MAKING HISTORY

By Stephen Fry

380 pages. Random House. $24.

Remember ''Springtime for Hitler,'' the campy, mock-Nazi musical in Mel Brooks's film ''The Producers''? It's hard to imagine such a tasteless idea actually getting off the ground in real life, but that is exactly what the new novel by the British writer and actor Stephen Fry aspires to do. ''Making History,'' which is being promoted as ''a thriller with a funny streak,'' uses Hitler and the Holocaust as fodder for an antic comedy about time travel and academic high jinks: the subject matter of ''Shoah'' seen through the lens, if you can believe it, of ''Back to the Future'' and ''Lucky Jim.'' The resulting novel is both shockingly tasteless and deeply offensive.

The plot of ''Making History'' goes like this: a bumbling graduate student in history named Michael Young and a professor of physics named Leo Zuckermann decide that the world would be a better place if Hitler never existed, and with the help of a time machine they use a male contraceptive to insure that Hitler is never born. As in a Ray Bradbury story, the results are not what they expected: with no Hitler to stand in his way, a charismatic maniac named Rudolf Gloder (a character invented by Mr. Fry) assumes leadership of the Nazi Party and uses the atomic bomb to take over Europe and the Soviet Union. He eventually concocts a monstrously evil plan, using the same contraceptives Michael used to prevent Hitler's birth, to wipe out all the Jews of Europe.

Faced with the horrifying consequences of their actions, Michael and Leo decide that they must reverse the events they set in motion. The remainder of the novel chronicles their efforts to ''make the world a better place by insuring that Adolf Hitler lived and prospered.'' It is a premise that inadvertently suggests that all evil is relative and that the six million Jews who died in the real-life Holocaust were an unfortunate but somehow acceptable number.

As his earlier novels like ''The Hippopotamus'' have demonstrated, Mr. Fry possesses ample comic talents, but in this volume he uses them to try to put a humorous gloss on one of history's darkest moments. The doctoral thesis written by his hero Michael, for instance, treats Hitler's life story as a schlocky comic novel. It depicts the sexual union between Hitler's parents that led to his conception; it shows the young Hitler trying to stand up to his domineering father, and it suggests that much of Hitler's character was simply a function of his dysfunctional family.