After a whirlwind ride downriver in a stolen rowboat, Dick Dodds discovers a strange trail in the black marsh mud. When he steps into it, Dick feels for the first time the cold shudder of "cemeteries opening up." From that moment on, he is haunted by the shadowy legend of King John's treasure lost in the marshes.

Dick meets Helen Johnson, who shares his fear. Frightened, yet intrigued by the eerie power of the trail, they follow where it leads. They are drawn into a mystery that takes them into the secret life of a small town and into dangers that reach a terrifying climax in the house on the brink.