What, you might ask, is acerbic social observer Mary McCarthy doing with a thriller about a terrorist hijacking-with-hostages? Answer: what she's always been doing--drawing elaborate caricatures of American types, squinting critically at behavior patterns among the upper- and middle-classes, and arranging political and esthetic debates. The hijacked plane is an Air France 707 headed from Paris to Teheran in 1975; and the target of the Dutch/Arab freelance terrorists aboard is an ad hoc international committee (seated in Economy) on its way to investigate the Shah's dreadful prison practices--a wry U.S. Senator (cheaply modeled on Eugene McCarthy), a shrilly chic college president, a sweetly kneejerking liberal Episcopal priest, an octogenarian bishop, a sleek Dutch politician, two professors (one is really CIA), and a young Jewish journalist. Why is this committee the target? Because, for hijack leader Jeroen, ""Seizing this body of self-appointed just men struck at the core of the West's notion of itself, at its proclaimed ideals. . . ."" But, as the plane is being forced to land in Holland, college-prexy Aileen nastily draws the terrorists' attention to a group of high-society art collectors in First Class (""It wouldn't hurt those millionaires a bit to be held for ransom. They could hand over their Giorgiones and Titians. . ."")--so both the liberal do-gooders and the mink-coated conservatives are transferred to a helicopter, subjected to a muddy nightmare night on a deserted highway, then spirited off to the terrorists' Dutch farmhouse hideout. And secret art-lover Jeroen, ""excited by the sheer beauty of the coup,"" now has a double plan: the rich hostages in exchange for their masterpieces, the political hostages in exchange for the usual political prisoners and such. Which is more valuable, immortal art or mortal life? Who are more loathsome--the babytalking Rich, the smartsy middle-class, or the terrorists? These are among the questions toyed with as the crammed-together hostages bicker, mind their respective manners, get smelly and wrinkled, and share the sadness of the Bishop's fatal stroke. . . . McCarthy, with her dense and snaky journalistic prose, has never been much for in-depth characterization; her cast of ugly and medium-ugly Americans here comes in various shades of colorful (but often quite dated) cardboard. And the plotting--especially a violent wrap-up--is arbitrary, unshapely, hardly suspenseful. The result is an odd, slow, rather stiff exercise that nonetheless keeps delivering little rewards (repartee, details, ideas), perhaps enough of them to divert readers with a McCarthy-ish leaning toward ironic meditation, socio-political skepticism, and elegant misanthropy.