A sinister story of World War II Intelligence so soundproofed you can hardly hear a footfall and so inferential you are not quite sure of what you've heard -- or overheard -- all dealing with Leach, the last survivor of a circuit which has been destroyed and Clare, newly trained in the skin games of betrayal and brutality. Mr. Markstein is a newcomer in the genre which he has seen fit to vary and well worth noticing.