I'm going to admit right up front that I have a bit of a soft spot for Larry Niven's Known Space books. When I was 13 years old, I found Protector on a dusty shelf in a library, and thus discovered my love of science fiction. Niven opened universes to me.Fate of Worlds: Return from the Ringworld (reportedly) wraps up Niven's classic Ringworld series and Niven and Lerner's Fleet of Worlds series, which functioned as a sort of sister series to the Ringworld series. The Fleet of Worlds books never quite achieved what the Ringworld managed. They were a bit too clever for their own good, required too much backstory and lacked the straightforwardness of the Ringworld books. Perhaps that was Lerner's influence, or perhaps both Niven and Lerner were a bit too ambitious in their plotting, but Fleet of Worlds never lived up to the brilliance of the Ringworld series.With that said, they were required reading for Known Space junkies like myself. The treachery of the Puppeteers, the surprising variety of aliens caught in the Puppeteers' plans and the fantastic exploration of space kept me reading. Fate of Worlds: Return from the Ringworld had all of the brilliance I expected of it and yet suffered from the same ills of the rest of the Fleet of Worlds series. The first half of the book is largely backstory. To call it a slow burner would be generous, but with 40-some years between the first Ringworld book and this (apparent) end to the series, there was a lot of backstory to cover. That said, once the story was sufficiently set up, it progressed quickly. This was a coming together of the many characters who spanned the series. Even those long-dead got a cameo appearance. And when the story ended, I had a tear in my eye.Fate of Worlds: Return from the Ringworld will not have wide appeal. Those new to the series would be quite lost. But for Known Space fans, it is sure to be required reading. With a wink and a nod to all that came before, Niven and Lerner have wrapped up 40-some-odd years of stories in fan-pleasing style.3.5 starsRead this review and more on The Library Lass Book Talk Blog.