A resourceful young sailor volunteers to command a battered bark and carry a priceless cargo to its destination, launching into a perilous sea voyage that ends with shipwreck and a trek into the San Blas interior. He and a small crew confront hostile terrain, enigmatic local tribes, and political intrigue surrounding a missing princess. Encounters include ambushes, skirmishes, desperate rescues, mysterious deaths, and acts of loyalty and sacrifice as they search for a hidden valley and valuable gems. The narrative alternates nautical adventure, jungle exploration, and episodic dangers culminating in an eventual departure from Panama.