THE LEVANTER
by ERIC AMBLER 307 pages. Atheneum. $6.95.
"As good as Ambler," say the cover blurbs on all those derivative thrillers that aren't. The Levanter shows why. Nobody else is quite so much at home down there behind the Middle Eastern gasworks where the real horrors breed, among the machines and crackpot politics and bills of lading, the irony and the ironmonger. Nobody but Ambler is quite so willing to risk boring us with the crucial facts—why the Russian rocket needs a special mounting flange to take a Chinese fuse, why it isn't all that simple to plot a new course for...