By a Time and Newsweek veteran Asia correspondent--a solid, unremarkable novel about politics-by-bribery and the largest opium cache in history. Michael Hudson lost the better part of an arm as a Marine colonel in Vietnam, where his closest companion was a French-educated Vietnamese major, Tran Li Phuong. Hudson also lost his wife and son in a car accident. Now retired on a disability pension, he accepts a posting to Thailand as a Special Assistant in Intelligence to the U.S. ambassador, Lansing Chalmers. Object: Hudson is to use his friendship with Tran Li Phuong, son of the top mandarin of the Triad (oriental Mafia), to persuade the Triad not to help a dissident General in overthrowing Thailand's pleasure-loving Prime Minister, Prince Korat. (Korat and others have been recipients of freshly decapitated human heads as a warning from the Triad.) And, when Hudson meets with Tran Li (he also happens to have fallen in love with Tran Li's beautiful sister), he is told of an unbelievable opium cache just across the Chinese border, a four-year harvest from World War II which the Japanese hid in a cave and which is worth billions as heroin. Will Washington help the Triad get the stuff, in return for which the Triad will ensure stability for Korat? Hudson has been empowered to agree, and Ambassador Chalmers later backs him up. So the Triad plot is hatched: an American B-52 (worth $20 million) must be crashed into a remote Himalayan peak, distracting the Chinese Air Force while an American chopper goes to the cave for the 20 tons of opium. Hudson and Tran Li lead the operation, but the climax is strictly Treasure of Sierra Madre, with stagily tragic overtones for Hudson. Intelligent thriller work, nothing very original--a sturdy story enhanced by fair characterizations and ripe Asian sketchwork.