NIGHTWORK by IRWIN SHAW 344 pages. Delacorte. $8.95.
Douglas Grimes is the unlikely hero of Shaw's high entertainment, Nightwork. A young pilot prematurely grounded by an eye ailment, Grimes answers the musical question: "What if $100,000 should fall into my lap?" That is almost literally what happens to him in the most improbable of settings the St. Augustine Hotel (semibitter religious joke here), a Manhattan charnel house where Grimes works as night clerk.
Fleeing to Europe, Grimes meets a Faustian figure (but a Faust with charm) named Fabian, who knows every banker, concierge...