Milo March is back with the C.I.A., Assignment--Russia, to find out what happened to agent Peter Hartwell: also if Richard Sorge is the head of the dreaded Fourth Bureau. Moonlighting in Moscow are four double and triple agents and Milo finds himself with ""an embarrassment of little helpers,"" not to mention a misplaced Syndicate man hoping for a heroin outlet. . . . More caution than action: more preventatives than cure. Milo has slowed down on everything but martinis.