In 1944, an American bomber, carrying dead navigator Paul Mandrake, crashes in the Swiss Alps. Twenty-one years later, his son, Peter, learns that Stephen Craddock, the family lawyer, should be guardian of his father's diamond university graduation ring, worth half a million dollars. Craddock, a sinister character, denies this. Is the ring still with Paul in the lost bomber? Peter is determined to find out, aided by his girlfriend, her geology professor and an old member of his father's Flying Fortress squadron. The search entails exciting climbing sequences and dangerous encounters with ruthless competitors for possession of the diamond ring.