An embellished account of the 1803 expedition by famed frigate U.S.S. Constitution--a.k.a. "Old Ironsides"--against the Barbary pirates then terrorizing American shipping, focusing on the crew and passengers of a fictional merchant ship, The Esther, who fall afoul of the same pirates and thus become involved with the Constitution's mission.

Inventor Harry Harper travels to the South Seas, where there is buried treasure belonging to a girl, Beverly West. Naturally, others are after the loot, and Beverly's father is being held captive by cannibals until she returns to them with a pearl that belongs to one of their idols. The climax consists of Harper saving Beverly from a safe which has been lowered into the sea.

A light-hearted romantic adventure.