Young Bill Berenger, having already won a considerable reputation for pulling off some difficult assignments involving detective skill, pluck and other assets, is this time involved in the machinations of a half-mad individual who calls himself the Fire-Seraph. This dangerous sort believes himself the descendant of the Incas and plots to dominate the world. Thus Berenger finds himself - to begin with - responsible for a cargo of explosives which the Fire-Seraph is hoping to secure for his own purpose. One thing leads to another and even when, after an air attack, Berenger's ship reaches its South American port and the end of the adventure might appear to have been reached, its most desperate episodes are ahead. Bill again meets his girl-friend Janet-Eve, and clearly a romance is blooming but before it can come to full flower, he has to take the biggest risk he ever ran in a situation that seems hopeless. Historic naval fiction and adventure for young adults.