Old Joe Cumberland is dying, and hanging on in hopes of seeing his foster son before he goes. But Whistling Dan Barry is gone, lost somewhere in the vast mountain-desert, an enigmatic ghost no one knows, not even Cumberland's daughter Kate, who is in love with him. When Dan is found, he is already embroiled in a revenge duel to the death with the fearsome mountain man Mac Strann, and only when that is finished will he return.