Humans have fordt contact, capture a monkey like alien.
Trying to identify a sci-fi novel I read years ago
I only remember the broad strokes:
Opening: Humanity's first contact happens when two alien ships are fighting near Earth (or in our system or a system near us) Only one survivor is recovered.
The survivor: A small, monkey-like alien. Very intelligent — teaches itself English with some help, picks up and learns information fast. Has a good realationship with its human captors understands why its being held.
Middle: Humans keep it imprisoned because they're afraid of a species with far superior technology. And this alien knows where earth is now. Through conversations, it tells them about a galaxy-spanning fascist empire that has enslaved thousands — possibly millions — of other species, all under the rule of a single dominant alien race.
The twist (late in the book): The "monkey" alien is actually a member of that evil empire. The whole sympathetic-prisoner act was a long con to get back to his people so they could enslave Earth.
Any ideas? I read it years ago and the title and author are completely gone from my memory.