An excellent science fiction novel written by Vernor Vinge, a prequel to the Hugo-award-winning A Fire Upon the Deep. It's hard to summarize the plot of a nigh-on-800 page book, but I'll try anyway. It's a story about a group of traders (members of a larger group known as the Qeng Ho) who take on a joint mission with a culture known as the Emergents. They are subtly betrayed and enslaved, many of their people being placed under a form of mind control, and must find a way to free themselves and save an entire newly discovered race from the same fate.

It's not nearly as cheesy as it sounds, either. Go read it, it's worth your time.