A solid, riveting prequel to Larry Niven's classic 1970 novel Ringworld, as well as several of that book's sequels, plus various related short stories and novels also by Niven, all falling under the "Known Space" label, 2007's Fleet of Worlds by Niven and co-author Edward M. Lerner (Small Miracles; Fools' Experiments) recounts how a group of humans under the rule of Niven's Puppeteer race (here called the "Citizens") tries to seek out evidence of their own race's history beyound what their alien benefactors have set down. Meanwhile, slightly insane Puppeteer Nessus (from the Ringworld novels) has his/her's own agenda, involving a group of renegade humans threatening the Citizens' empire.
The action takes place on several worlds and in space (fans of Niven's previous works will meet a few familar alien races). Niven and Lerner manage to successfully blend exciting storytelling, believable characterzations (the backstory of the main human protagonist, Kirsten, is especially well developed; for a change, the reader meets an actual strong female character in a "hard" science fiction novel) and use of scientific principals (like "klemperer rosettes"). If you're a fan of Niven's previous work or if you just want to read one of his "Known Space" books, Fleet of Worlds (the title refers to the Puppeteers' home planet Hearth and their neighboring agricultual worlds grouped in a klemperer rosette formation ) is a good call.