Here's a book that most people wouldn't think is a mixed between thriller and romance. It's called 'The Plains of Passage' by Jean M. Auel. The book is in a series with the first one called 'The Clan Of the Cave Bear', the second one called 'The Valley of Horses', the third one called 'The Mammoth Hunters', and the fourth one called 'the Plains of Passage'.
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“In a world where you can be anything, be yourself.”