He's conquered Broadway (The Mystery of Edwin Drood), TV (Remember WENN), and pop music (''Escape [The Pina Colada Song]''). Now Holmes ventures into novels with a '70s-set showbiz whodunit: Miss O'Connor gets embroiled in a murder mystery while ghostwriting a memoir of a fading star best known for his years with a pratfall-prone sidekick. (Except for the bit about a dead hotel maid in a bathtub, the duo sound a lot like Dean Martin and Jerry Lewis.) Between Virginia Slims and vermouth, Miss O proves quite the Nancy Drew -- although Nancy never bedded her suspects. And thanks to her freewheeling voice, Truth is engrossing from start to finish. Just don't lend it to your Sue Grafton-loving grandma -- the menage a trois with a theme-park Alice in Wonderland might be too much for the old gal.