There are no happy novels set in Berlin, but Harris (Selling Hitler, 1986, on the diaries forgery) has managed a novel that dances on Hitler's grave with amusing success. Naturally, the whole book is entirely depressing, depression being the keynote of Hitlerian fantasias; its leading tones were struck earlier by Orwell's 1984 and le CarrÇ's The Spy Who Came in from the Cold. Harris's novel is set in 1964--Germany has won WW II, and this is the weekend of Hitler's 75th birthday, with huge celebrations ready to blow. After defeating Russia, Germany has formed a European trading bloc with 12 Western nations; German is the second language in all schools; everyone drives German cars, watches German TV, and so on. Switzerland alone is neutral, afloat on the Wehrmacht's stalemate in its cold war with the US. Tying in with Hitler's birthday is the announcement that--to reinforce dÇtente between the two countries--US President Joseph P. Kennedy has been invited to Berlin. But that dÇtente is threatened by the murders of two retired high officials, and Xavier March, homicide investigator with the Berlin Kriminalpolizei, lands the job of tracking down the killers. March is divorced and disaffected, and his ten-year-old son hates him for not being a super-Nazi like himself. Just as March is getting ahead in the case, he is taken off it by Globus, a top pig in the Gestapo. But March is too far in to stop. And he's fallen in with the beautiful American journalist ``Charlie'' Maguire, a smart and feisty woman who's always ready to prick March's Nazi chauvinism. The big secret: March has stumbled on the great Nazi coverup of the gas chambers, with ghastly proofs of it hidden in a numbered Swiss account. Farsighted readers know that massive dystopian evil such as Winston Smith faced in 1984 can provide no happy end. But only a Schweinehund wouldn't like this springtime for Hitler, with its waltzes through the Holocaust to the tunes of Leh†r's The Merry Widow.