From the introduction:
In 1955, the Govt set up Area 51, a giant area in southern Nevada where strange lights and sounds are occasionally seen and heard for miles around. Nearby towns have been evacuated, quarantined, and cut off from the world. Rumors of alien technology run amok start small, grow larger, and are then silenced. The President has come on the radio many times to explain to the citizens that the Govt has the situation well in hand. He assures us that, although details cannot be released for security reasons, our best men are hard at work in Area 51, following a plan to make America stronger and safer than ever.
By late 1957, a strange structure at the center of Area 51 has grown tall enough to be glimpsed from beyond the wall. It looks unearthly. The Govt refers to it as a project. The doubters refer to it as The Ship.
It is now March, 1958. The bright lights, incessant buzzing and thrumming, and occasional flashes of Area 51 all suddenly stop. Alarms sound briefly and then are silent.
This is your opportunity.
There are three of you: a Crusader, an Expert, and an Innocent.