From the back cover:
"It's 490 light years to Beta Centauri. You have a full tank of rocket fuel. Half a charge in your Proto-cyclotron Blaster. It's dark. And you're wearing your sunglasses.
Provides directors with more aliens for their players to track down. Within these recently declassified folders you will find 25 new alien races ready to use for your campaigns. Some of them are well known to the MiB, some are virtually unknown... to everyone.
Detailed information on a couple dozen aliens, including game stats, background info, variations, and notes on including them in adventures.
Dossier sheets for aliens, characters and debriefing
a dozen die-cut Resident Alien IDs for the races described."