When popular British adventure author Bagley (The Enemy, Flyaway) died in '83, he left behind this characteristic thriller, a tightly packaged tale of a geological treasure hunt in the South Seas. As is usual for Bagley, clear-cut heroes and villains play their parts here in a morally certain universe where the well-bred Englishman is king. In this case the embodiment of British values is stouthearted Mike Trevelyan, an oceanographer who learns that his older brother, Mark--who shared Mike's profession but not his morals--has died of appendicitis on a small Pacific isle. Knowing that Mark had lost his appendix years before, Mike smells foul play. The stink grows when thugs steal Mark's effects during a bloody robbery in which Mike displays extraordinary fighting prowess (for Bagley, a genetic trait of the English) and kills an intruder. But the robbers miss two items: Mark's diary, and a manganese nodule, common enough on the ocean floor but rarely containing the 10% cobalt content of this one. Taking clues from the diary, Mike surmises that Mark had stumbled upon a trove containing billions of these rich nodules and had been murdered by his partners, now after the deposit. With some tough sailing pals and a wealthy mining investor, Mike sails to Tahiti and beyond to find both the treasure and the killers. The thugs who stole Mark's effects sail in pursuit, murdering several of Mike's crew in pitched battles. After a long voyage punctuated by these killings and a very proper romance between Mike and the investor's lovely daughter, Mike and crew finally locate the manganese/cobalt deposit, only to have Mark's partners, blackguards all, commandeer the ship. But, in Bagley's customary blowout ending, the deposit happens to lie atop a percolating volcano. The volcano erupts; Mike's quick wits and fists save his ship and crew as the villains cook in the deadly lava flow. A satisfactory, if unspectacular, legacy of Bagley's solid craftsmanship.