After reading about the Ringworld, I saw the Protector being referenced in the second book. I thought to myself, but I have a Niven book about a Protector, maybe I need to read that before reading more Ringworld books. So I did. This is a pretty short story, divisible into two parts.
In the first part of the book humanity lives throughout our solar system, divided in Earth and the moon, and the Belt, where people live in space all their lives. One day, while detecting monopole magnets, the first Outsider, alien, is spotted. This is a protector, who has travelled 32000 years to find the colony of Pak aliens who were stranded near Sol 2,5 million years ago. And he finds us. And Brennan, the first human he meets. The second part of the book takes place a few hundred years later when humans are kidnapped every now and again, disappear for four month and then return with amnesia. The Protector has something to do with that, and all will come to a climax to protect the human race.
Even though the book felt rushed, it was very enjoyable. I would have liked it if most parts were fleshed out a bit more, but I know that some of the philosophy behind the Pak Protectors and humankind comes back in the Ringworld books. Four out of five stars, and a must read for Ringworld fans.