The thaw which has moved gradually across Eastern Europe and the Soviet Union during the last generation came most slowly and grudgingly to East Germany, where the imported heritage of Stalin mingled most compatibly with the native tradition of Hitler. The wall thrown up almost overnight across divided Berlin and more slowly along the border between the two Germanies made horribly concrete Winston Churchill's metaphor of the "Iron Curtain" and gave John Kennedy the material for one of his finest pieces of rhetorical understatement: "Freedom has many difficulties and democracy is not perfect, but we never had to put up a wall to keep our people in."

The statement is both the epigraph and the final sentence in "Day of Judgement," a work of escape fiction in more than the usual sense. The time is 1963, Kennedy is planning his historic trip to the Berlin Wall and his "Ich bin ein Berliner" speech, and Ulbricht government has hatched a plot to counteract the negative propaganda that will result from this event: Kidnap someone prominent in the moving of refugees from East to West, brainwash him and put him on a showcase trial that will reveal the true face of Western "imperialism" in all its "fascist" horror.

The story has considerable depth and complexity, the cast of characters variety because the victim of this plot is a Jesuit priest, Father Sean Conlin, a veteran of Nazi concentration camps and a man familiar with the "thought reform" processes that are used on him. While the basic story is that of a rescue operation, Conlin's presence enables Higgins to stage an absorbing metaphysical battle of minds in a German dungeon, to involve East Germany's Christian underground, and to make the dying Pope John XXIII one of the secondary characters.

The rescue itself is a model of its Rube Goldberg kind and clearly designed for easy conversion to film. One way you can assess the commercial filmability of a book (as action films are made these days) is to count the number of motor vehicles used in it "Day of Judgement" includes not only a fair quota of routine automobiles and trucks, but lots of motorcycles dashing around, an ambulance, a hearse and, most spectacularly, a small vintage airplane (a Fiesler Storch) making a quick illegal excursion across the border and engaging (unarmed) in an epic battle with a MIG.

There also is a tunnel. Novels about the removal of people from East Germany tend to have tunnels, but this one is special; it goes under a graveyard, with sometimes ghastly effects when the diggers encounter a grave of a certain vintage. The tunnel links a monastery and a castle, which stare Balefully at one another across a small East German village-the castle taken over by the government and being used, at the moment, as a brainlaundry; the monastery slowly shriveling out of existence under the relentless pressure of a hostile regime.

Besides the scenery and hardware (key ingredients in the contemporary action-suspense story), Higgins provides a cast of larger-than-life characters; Conlin, struggling through his dark night of the soul; his adversary, Harry Van Buren, renegade American psychiatrist and "expert in thought reform" - brilliant, cynical, bitter; Major Vaughan, free-lance cloak-and-dagger expert to whom it is "a matter of supreme indifference . . . whether he lives or dies."

Finally, there is Father Erich Hartmann, S.J., of the Catholic Secretariat in East Berlin. He is a giant of physical and moral strenght but also what Vaughan calls a "holy fool." If the battle of the Storch against the MIG is the action climax of the book, Hartmann's showdown with the Volkspolizei (the Vopos) is its moral climax-an intense, symbolic confrontation of Church and State in which the State carries a gun and the Church carries only a cross.

Higgins has brought together a rich mixture of ingredients, and a plot which is implausible - particularly when one considers what was actually happening in East Germany in the Early '60s. He is a master at involving his readers in the fate of his characters and in the storyteller's most basic art-keeping alive the eagerness to see what happens next. He manages to put the Catholic Church into a suspense novel with more expertise than anyone else who has tried in recent memory except Morris West, and if he makes an occasional slip in small details (putting a "zapata" rather than a zucchetto on an archibishop's head, for example), this is not likely to bother most of his readers.