Edgar Rice Burroughs, the classic adventure writer is most famous for his Tarzan and John Carter (Barsoom) series. The Eternal Lover is in my opinion, one of his most unique and original adventure stories.
The novel begins with Nu, a prehistoric human hunting a sabre-tooth tiger. He plans to gift the animal's head as a trophy for his mate. However an earthquake, occurs and Nu collapses after finishing his hunt.
Somehow he survives the event wakes up in 20th century Africa, searching for his long lost love. The premise might sound ridiculous but ERB crafts an entertaining adventure story with memorable action scenes and landscapes. The switching perspective from modern time to Stone Age keeps the story entertaining. The highlight of the book is the ending, which is quite powerful and lends credibility to the romance.