Frail and bookish Waldo Emerson Smith-Jones is swept ashore on a remote island, where he encounters Nadara, a mysterious young woman living among primitive tribes and dangerous beasts, and is drawn into a desperate struggle for survival. Once timid and physically weak, Waldo gradually transforms into the formidable warrior known as Thandar as he fights to protect Nadara and searches for her when they are separated, while their shared hardships deepen into love. After repeated dangers, battles, and reunions, the pair begin to imagine a future together only to fall into captivity once more, setting the stage for an even greater struggle.