by Viking, $17.95. Mr. Greene’s latest novel lacks something of the compulsive drive that one expects of this distinguished author, perhaps because the principal characters are seen entirely through the eyes of a mildly baffled third party. The narrator is unaware that he is cast as combination page, squire, and go-between in a contemporary version of the old theme of loyal knight and unattainable lady. The captain—his very casual surrogate father—is a basically decent fellow for whose outmoded talents modern society has no decent use. He is, in short, an international crook. The lady, like most of her kind, is remarkable only for her ability to inspire devotion. It is unlikely that these misfits can prevail against such dragons as English policemen and Latin American politicians, and Mr. Greene is much too accomplished a novelist to permit them to do so..