Best of the new soft-covers; Loony Latin 'soap-opera'; Aunt Julia and the Scriptwriter, by Mario Vargas Llosa. Translated by Helen R. Lane. New York: Avon Books. 374 pp. $3.95.

An uproarious entertainment by the Peruvian author who has so arranged this blend of youthful autobiographical elements and fictitious soap opera installments that no one can miss the parallels. During the 1950s, 18-year-old Vargas Llosa, law student/part-time radio newsman/struggling author, lives with his grandparents in Lima in the midst of a virtual small town of an extended family. Enter two larger-than-life figures: his 32-year-old aunt-by-marriage, Julia; and the Balzac of modern radio serial drama, Pedro Comacho. Fascinated by the mature charm of the one, by the fanatical devotion to art of the other, Mario is drawn into closer company with each. For sheer entertainment, wit, imagination, and high style, this soap opera of Love and Art can't be beat.