Fleet of Worlds by Larry Niven and Edward M. Lerner

I loved Larry Niven's Known Space series when I first encountered the stories in the late 1960s, and the jewel in that crown - Ringworld - remains one of my favourite SF novels. I thoroughly enjoyed a re-read a few years ago. It's been a long time since I read a new one, though, and I approached Fleet of Worlds with some trepidation. Not only because of the length of time since the concept was fresh but also because this one (first published 2007) was written in partnership with another author. In my experience, sequels of much-loved books written in these circumstances are generally not worth bothering with. Fortunately, this one proved to be better than I feared. However, prospective readers should read Ringworld and preferably some of the earlier Known Space stories first, otherwise they will miss a lot of the references.

The story is set 200 years before Ringworld but the prologue takes place 500 years earlier still, on a human sub-light speed starship with a cargo of thousands of embryos on its way to colonise a planet of a distant sun - a voyage which is abruptly interrupted. The setting then jumps forward 500 years to the Puppeteers' cluster of Home Worlds in their long flight from the supernova explosion in the galactic core (as described in Ringworld). But the Puppeteers are not the only inhabitants of their worlds - one of them contains a large colony of humans who work for them. It becomes apparent that the humans are the descendents of the colonists in the starship. The Puppeteers had taught them English but, anxious to keep the location of their Home Worlds a secret from any potential threat, had preventing them from discovering anything about their origins or the location of Earth.

The plot concerns the efforts of some of the humans to outwit the Puppeteers and discover their origins, mixed with internal politics of the Puppeteers (in which the character of Nessus, familiar from Ringworld, has a starring role). There is also some Puppeteer meddling with affairs on Earth, where they are already known for selling the invulnerable General Products spaceship hulls. The paranoid Puppeteers are desperate to prevent their tame humans and the Earth humans from finding out about each other, for fear of the reactions on both sides. They are prepared to go to any lengths to preserve their security, revealing a darker side to their engaging personalities.

Inevitably, the story lacks the freshness and originality - and the sheer sense of fun - of Ringworld and the other original Known Space books and it took me a while to get into it, but I became increasingly engaged as I read on. Not a ground-breaker, but worth the read. I note that there have been three sequels: Juggler of Worlds published in 2008, Destroyer of Worlds in 2009, and Betrayer of Worlds in 2010. I'm not going to be buying all of these in one go, but I think I'll try the next one to see how the series develops.