For some time now, writer-actor-performance artist Spalding Gray has been carrying around with him a monster: a manuscript of a novel called Impossible Vacation, a book that at last sighting weighed in at about 1, 800 pages. Monster in a Box is a guided tour between the stations of his writing block, which include a field trip to Nicaragua, a disastrous guest appearance at the Moscow film festival, and a stint in Los Angeles hunting down the fabled few who have never written a screenplay. Hilarious and poignant, Monster in a Box is further proof that Gray has not only captured the dangerous spirit of our age but swallowed it whole.