When he finally gets to his central question, Stephen King asks a good one: "'Just suppose you could hop into a time machine and go back to the year 1932. In Germany. And suppose you came across Hitler. Would you kill him or let him live?'"

When the question is first asked by the hero of "The Dead Zone," Johnny Smith, the answer seems self-evident. One war veteran takes out an old knife and says he would put it into Hitler's heart, "as far as she'd go . . . and then I'd twist her . . . But first, first I'd coat the blade with rat poison." Others are less sure, less violent.

For Johnny, the question is not hypothetical. He has seen not Hitler but a man perhaps even more menacing -- Greg Stillson, New Hampshire congressman, liar, cheat and sadistic brute, who has come to power through intimidation and blackmail and who has hired members of a motorcycle gang as his bodyguards, the nucleus of his personal SS.

All this is bad -- and Johnny, a conscientious and rather scholarly type, has also researched a wealth of disturbing information on Stillson's earlier life. But worst of all, he has shaken hands with Stillson and, in that moment of contact, had a vision: years in the future, Greg Stillson has become president of the United States, and he starts a war that ends with the total destruction of life on earth. In comparison, Hitler was a mild headache.

Clearly, Johnny has a problem: Do you kill a public servant because you have had a vision? How many men have become political assassins for reasons like that -- and what is the world's judgment of them? But even more fundamentally, Johnny is not a killer; he is just a man who has occasional, clouded glimpses of the future and sometimes acts on them.

Johnny's visionary batting average has been pretty good, since the long-ago time when he stood in front of a roulette wheel and discovered that he could guess which number was coming up next. He has predicted that a sick child would be cured, helped a friend to track down a lost relative, noticed that a house in the next town was about to catch fire and called the fire department in time. Most impressive of all, he saved the lives of most of the high school graduating class when he persuaded them to come to a private party after graduation. Those who ignored him and went to the restaurant where everyone had reservations ended up as victims when the restaurant was destroyed by lightning.

Besides his moral dilemma -- to shoot or not to shoot -- Johnny's special ability plunges him into personal problems. He discovers that people are usually more scared that grateful when you barge into their lives and mess them up with predictions that come true.

Establishing this final point, Stephen King also manages to slip in a little bit of self-promotion when one of the students Johnny has saved turns on him in a hysterical tirade: "It's his fault, that guy there. He made it happen. He set it on fire by his mind, just like in that book 'Carie.' You murderer. Killer You . . ."

"Carrie" is, of course, one of King's earlier books; like "The Dead Zone," "The Shining" and others, it deals with the theme of "wild talents," special powers that cannot be explained by science. This is a kind of writing that many readers find abhorrent, but King manages, nonetheless, to hit the best-seller lists and the big book clubs. His success is hard-earned; he does not overplay the psychic oddities that are the chief attraction and the major drawback of his work, and he immerses his basic improbabilities in a mixture of character, locale and incident rich enough to attract many who ordinarily do not care to read about minds that can see ghosts, perceive the future or set a town on fire.

Such minds are, nonetheless, his central concern, and the open-minded reader is likely to end one of his books with a feeling that, if such things were possible, they would probably feel and function as King describes them.

In "The Dead Zone," besides the central moral dilemma which he sets up and solves quite satisfactorily, King presents an interesting picture of small-town life in New England, a powerful if somewhat overdrawn account of the rise of a venal politician, and a small tour de force in which he manages to make interesting the 4 1/2 years Johnny Smith spends in a coma. It is not a book that will please everyone, but those who like it will probably like it a lot.