By his two-hundredth birthday, in the year 2850, space adventurer Louis Wu has achieved fame and fortune and explored the vast reaches of Known Space. Thanks to the anti-aging effects of boosterspice, he's in perfect health and looks no older than a man in his twenties. He should be happy. Instead, he's bored. What's left to do when you've seen and done it all? Enter a two-headed alien Puppeteer known as Nessus, who makes Louis an offer he can't refuse: to lead a crew on a mysterious mission beyond Known Space. Joined by a motley team that includes the alluring earthling Teela, who has been genetically bred for good luck, and the fearsome catlike warrior Kzin known as Speaker-to- Animals, not to mention the finicky fraught with wonder, danger, and wild adventure. When their ship crash-lands on the Ringworld, a one-million-mile wide artificial ring that encircles a star, Louis and his companions discover that their perils have only just begun.