Authentic deep-sea-diving action enhances this otherwise routine treasure-hunt melodrama from the author of The Heights of Rimring. Martin Newman, a top-flight diver who's been hired to explore a secret German mountain mine which is five levels deep with flooding, discovers 36 steelcases behind a steel door on level five. But before Newman can organize their removal, his crew and equipment are blown up while he's still below: he awakens in a strange hospital, escapes from Soviet captors, is befriended by some anti-Soviets, and is sneaked to freedom in a gas container. So, once back in the West, Newman is determined to get some answers. And when Eurosalz, the company that hired him, seems no longer to exist, he goes looking for that secret mountain mine again. Joining in Newman's hunt: beauteous, tri-lingual Anna, who becomes his secretary-lover and helps him to track down David Westman, an American involved with Eurosalz. . . and with the collection of ancient Greek treasures! Could the treasure on level five therefore be Schliemann's gold of Troy--secreted by Goering back in Nazi days? So it seems. And the big dive finally comes off. But traitor Anna drives the truck straight toward the very near Russian border--and some familiar ironies ensue. Predictable most of the way through, then, but competent in its stolid fashion and solidly suspenseful when the five-level diving is in the fore.