Larry Niven & Gregory Bentham 
Shipstar [EPUB ebook] 

When a landing party is sent to find out why, the Shipstar is on the same trajectory as a human party, half of the group is captured, the other half must go on the run from the bizarre inhabitants. The free group must find a way off of the object and back to their vessel. In the course of their attempt, however, they will uncover the secrets of the Shipstar—secrets that will forever upend their understanding of the universe, and mankind’s place in it.