In fact, it's hard to know what to call this book. It starts in the grave of a woman named Giselle, who has been murdered by her husband, and who slowly becomes aware that she is fated to haunt him. There's a lot of literary trivia and a lot of clever literary allusion concealed in the book, but there is no impulse to suspend disbelief and believe these things while the reader is in the midst of them. The reader is too distanced by the self-conscious literary gamesmanship from feeling any of these horrors. It's difficult to acquit Mr. Disch of the sin of writing with one eye on the literary critic and the other on the syllabus of the ''modern fiction'' courses in college classrooms.
Horror fiction is, let's face it, an entertainment genre.
It should be taken on its own terms. Not, that is, until I read the Disch novel. I am no aficionado of the horror genre per se. I still think, as per Shaw's admonition, one should take it with the most tragic solemnity or let it alone altogether. Judging by ''The Businessman,'' Mr. Disch should have let it alone.