Ringworld Engineers

Louis Wu and Chmee (formerly Speaker to Animals) are kidnapped by the ousted Hindmost Pupateer to help it find some left over super technology which will put the Hindmost back in charge. Only trouble is not only does it not exist but Ringworld has developed a wobble and is about to crash into the sun, only little Wu and the wookie look-a-like can save trillions of inhabitants, but first they have to save themselves from the betrayed Hindmost and the Pak Protectors who built the Ringworld.