When the Pan American airboat Hawaii Clipper left San Francisco in July 1938, one of its twelve passengers, says Jackson, carried money for Nationalist China. The Clipper vanished and was reported ""lost at sea""; he claims--unconvincingly--that it was hijacked by Japanese. Much of this book is a review of Pacific politics, describing the Thirties' tensions which could have spawned such action. U.S. Pacific defenses were weak; Japanese hegemony over Micronesia was increasing; officials felt war was imminent. Pan American's quest for Pacific routes, Jackson claims, provided the perfect cover for fortifying U.S. holdings (Hawaii, Midway, Wake, Guam), so lucrative government postal subsidies were forthcoming. (Similar support was provided, however, for other Pan Am overseas routes.) There were rumblings of protest against the flights in Japanese newspapers; and Jackson also cites some tenuous sabotage attempts. Against this background he asserts that two Japanese officers boarded the Hawaii Clipper in Guam and hijacked it to a Micronesian island, both to intercept the Chinese money and to get a model for an airboat of their own. He dismisses the idea of storms, mechanical failure, bombs, or artillery attack because no traces of the plane were found. ""Hijacking cannot be conclusively proved without a confession or demonstrable evidence,"" Jackson admits; but on the basis of political and ""physical"" factors, ""it is the most credible explanation."" There the story ends, with too many serious questions left unanswered--the fate of the passengers? postwar investigations?--to make it more than an intriguing speculation.