Here are three novellas of escape and exile, touching and funny and at times calculatedly outrageous. In "Saturn Street," a disaffected L.A. screenwriter delivers lunches to homebound AIDS patients, only to find himself falling in love with one of them. In "The Wooden Anniversary," Nathan and Celia - familiar characters from Leavitt's story collections - reunite after a five-year separation. And in "The Term-Paper Artist," a writer named David...