Indigo Island and Pinckney Plantation are sweltering under the South Carolina sun as tourists invade in advance of the Fourth of July holiday. But when three cousins who fancy themselves amateur sleuths come upon a long-ago runaway's skeletal remains, the cold case casts a chill on summer fun. Still, it doesn't keep the cousins from planning for a parade and a picnic even as they dig into the island's haunted history while hunting for treasures at an estate sale.