A novel by Larry Niven, first published in 1996. It is the direct sequel to his previous work The Ringworld Engineers (1980). He wrote it as a replacement after being unable to finish his contracted novel The Ghost Ships, the sequel to The Integral Trees and The Smoke Ring.
This book consists of two main plot threads, which only come together towards the end of the book. The majority of the first half of the story is devoted to a plot where a variety of hominid species from the ring join together to kill a large nest of vampires (the shadow nest) which has been feeding on all of them. Some of the characters are also found in The Ringworld Engineers, as early on in this book Niven tells us that relatively few of the hominids died when Louis Wu and the Hindmost restabilised the ring at the end of the previous book.
The second part of the book details the continuing adventures of Louis Wu, who is now aging and ill. Eventually he returns to the Hindmost and is restored to health, only for the pair of them to be enslaved by a vampire Protector, along with a Kzin named Acolyte, son of Chmee. What follows is a power struggle between Protectors on the rim wall and the vampire Protectors who have control of the Ringworld's defences. In many of the situations in this section of the book, Louis, the Hindmost and Acolyte are present only as observers, as it is the Protectors who are the main protagonists of the story.
Ringworld Prequel series (Larry Niven and Edward M. Lerner?)
Ringworld (Larry Niven)
More: The Ringworld