From the back of the module:
Prime Base is TimeLine Ltd.’s module of the lost control and command center for The Morrow Project. It is designed exclusively for experienced players and Project Directors. There is no bolthole in this module, it assumes that you have an experienced team ready to take on the most important Morrow Project mission to date: Prime Base.
Prime Base is unlike any previous Morrow Project module. It is bigger, more detailed, more difficult and more deadly. It is the turning point for the Morrow Project. The point at which The Project begins rebuilding North America. The data, equipment, and plans which will awaken th sleeping potential of the Project wait at Prime Base. The Team which can survive will unlock its secrets.
This module contains a complete description of Prime Base and its environment including maps, room-by-room descriptions, new equipment, complete play of the game for the Base and more. It has history of the Base up to and including its final days. Everything is included for the Project Director to run the biggest Morrow Project module produced to date.