(FORTUNE Magazine) – War is hell. Investment banking is too. Franklin Leib knows, since he has been at the front in both. But writing's not so bad, so Leib, 44, a vice president at Bankers Trust and a Vietnam vet, decided to retire from the trenches of finance to launch an assault on literature (he also does some consulting). His first novel, Fire Arrow, is a military thriller about a hostage rescue in the Libyan desert and the political posturing surrounding it. The book has done well critically and financially: Book-of-the-Month Club plans to feature it, and Leib picked up $600,000 for the paperback rights. John Ehrlichman, no stranger to political posturing, praised Fire Arrow for ''believability, suspense, and its thoroughly sensible ending.'' Leib did painstaking research to guarantee that authenticity. He spent time with the 82nd Airborne Division at Fort Bragg and pored over training manuals to make sure of his facts. Some of the details of the book's rescue operation could be insider stuff, since Leib was in Naval intelligence, but he's not talking: ''Those operations were classified, and no records of them exist.'' But he does say he borrowed from his military experience: ''In war you have to be able to deal with the unpredictable. It's just like a bond deal.''