Set in the fabulously catty world of glossy women's magazines, Kate White's first mystery, ''If Looks Could Kill,'' was a cheeky, well-received romp. Her sophomore effort, A Body to Die For, again starring no-nonsense (and often horny) reporter Bailey Weggins, revisits familiar territory, this time a murder in a luxe Massachusetts spa. White, the editor in chief of Cosmopolitan, details the finer points of Ayurvedic treatments and sento baths with an insider's assuredness. And even non-Cosmo readers can appreciate the scandalous twists: ''Happy ending'' massages! Teenage sex! Death by seaweed wrap! As fun and frivolous as a champagne facial.