Phantom of the Kremlin : THE KIROV AFFAIR <i> by Adam B. Ulam (Harcourt Brace Jovanovich: $19.95; 416 pp.) </i>

If there were such a thing as original sin in the Soviet Union, it might be the murder of Sergei Kirov at Communist Party headquarters in Leningrad on Dec. 1, 1934. From this murder, many historians assert, flowed the purges of old Bolsheviks, of the military and of as many as 10 million Soviet citizens in the late 1930s. From it grew the permanent apparatus of terror that made the Soviet Union what it is today.

In this vein, Adam B. Ulam, a Polish-born Harvard professor most noted for his biography of Stalin, has written a novel in which Kirov’s death haunts today’s Politburo. Ulam’s man-in-the-middle is Politburo member Mikhail Kondratiev, a sophisticated Marxist with the tastes of an upper-class capitalist consumer and the ruthlessness of an old-time Communist commissar. Kondratiev is obviously a composite bureaucrat, embodying elements of the late, largely unlamented Yuri Andropov and other top dogs, perhaps including Mikhail Gorbachev. As the novel opens, Kondratiev is heading home from Geneva to Moscow where he is about to make a move for the top spot.

It is Kondratiev’s misfortune, as Ulam reveals in flashback chapters, to have been in Leningrad party headquarters the night Kirov died. Because he knew too much, young Kondratiev was lucky to have been shipped to a factory in a provincial city rather than executed. Ulam intertwines Kondratiev’s rise and Kirov’s fall in a way that will intrigue thriller-lovers and perhaps surprise historians who remember Ulam’s previous dissident view that Stalin did not engineer Kirov’s death.

Revisionism aside, Ulam has done a first-rate job of building history into a novel that uses action and dialogue entertainingly. When the book turns to the fear and trembling of everyday life in 1930s Russia, “The Kirov Affair” is at its best, an interesting companion-piece, in this regard, to Anatoli Rybakov’s more widely heralded “Children of the Arbat.”

Ulam may have written his novel largely as speculation on the secrets of today’s Kremlin. But somewhere he has learned how to keep a plot oiled and running--while remembering a bloody story that some in the Soviet Union would happily forget.