One of those wearever action stories of World War II written with more proficiency than most and, even where it may never surprise you, it will manage to retain your interest. It's set in the once jewel-toned seaport of Piraeus, more and more beleaguered as the hostilities go on here swiveling between two M.I. 6 agents, Germans of all stripes, one Viennese lady of sorts skilled in the pleasures of the evening, and particularly Petros Zervas, a former illegitimate operator now recruited first to salvage the ikon of Black Saint Nicholas and then commandeered into serving the Allies as a saboteur. He's the man with the equally black worrybeads. The windup involves an attempt to sink a convoy at a price which includes Petros. You'll be sorry to see him go. . . . Good enough of its kind although the publishers think it's better than most and expect it to click like those worrybeads.