Newly married David and Catherine have pioneered their own Club Med. on the Riviera. It is the perfect place for a sea.

             change. The couple spends golden days brunching, mixing drinks with Perrier, wearing fisherman shirts and espadrilles, swimming and tanning in the buff.

             The rate of exchange is very favorable.

             The trouble in paradise is that David is on the threshold of literary fame while the beautiful and rich Catherine is jealous of her husband's reviews. She is also sexually unsettled. In bed with David, she wants to be a boy. She then persuades her husband to join her in getting matching short haircuts and a platinum - blond dye job. (Hemingway fans may recall that the Catherine of A Farewell to Arms also suggests twin coiffures but without the bleach.) Eventually, Catherine comes out of the closet on the arm of the dark,lovely and rich Marita. ''All things truly wicked start from innocence,'' Hemingway once wrote. Adam and Eve got the message late, and so do David and Catherine. Her kittenish antics turn savage. She thrusts Marita and her husband together with predictable consequences and then strikes out at both of them. The situation is somewhat similar to the time Hemingway and his first wife Hadley spent a summer.

             living with Pauline Pfeiffer, a Paris Vogue editor who was to become the second Mrs. Hemingway.Yet Catherine shares some of her most unbecoming characteristics with Zelda Fitzgerald, the envious and unbalanced wife of Hemingway's pal F. Scott. If Hemingway had completed this romance, perhaps Catherine would have had more than two dimensions. The first is what Edmund Wilson called ''the all-.

             too-perfect felicity of a youthful erotic dream.' The second hinges on the age-old view of woman as the cause of original sin. Catherine is a spoiler whose taste in forbidden fruit threatens the private Eden of David's art. It is the place where he struggles with his own lost innocence.