"There's part of Bud's wrecked plane!" Hovering his new cycloplane, the Drumhawk, in turbulent skies above the wilds of the New Guinea jungle, Tom Swift Jr. points to the sheared-off wing of his friend's plane. The area, flanked by two extinct volcanoes, is as forbidding as the deserted native huts clustered in sinister shadows.

Without Tom's latest aircraft, which uses ultrasonic rotating drums to provide lift, a rescue attempt would be impossible. Battling violent weather conditions, the young inventor lands the Drumhawk and organizes a rescue expedition.

Hazards are encountered from hostile natives who fire barrage after barrage of razor-sharp stone missiles and from a scientist with a deadly ray weapon. Tormented constantly by crafty enemies and nature's perils in the search of Bud, the rescuers unearth a clue that the young pilot is a prisoner of an unscrupulous group of white men who have discovered a fabulous ancient secret and are utilizing it for nefarious purposes.

How Tom, at the risk of his own life, outwits Bud's captors and opens up a new field for science makes tense, exciting reading.