At Fort Matanzas National Monument in St. Augustine, Florida, a young explorer searches the clear waters of the Matanzas River at sunset. Coming up for air and to check on his young brother, he quickly returns to his task, hoping for Spanish Treasure or signs of the massacre that took place on the park's shoreline 450 years ago. The massacre, which gave the fort and the river its name, looms in the imagination of boys both young and old.