Once before, aliens tried to take over the Earth. That time, their diabolical House of Doors, a torture chamber designed to test a native species' intelligence and adaptability, was defeated by a small group of humans. Acting according to their own moral code, the aliens withdrew from our planet, acknowledging our right to survive.

Now a renegade group of aliens has returned, intent of transforming Earth into an alien breeding ground.

Mankind's only hope is to reunite the adventurers who first solved the puzzle of the House of Doors. Led by Spencer Gill, whose understanding of machines verges on the supernatural, these intrepid heroes will battle their way through the House's deadly four-dimensional maze. They will be their own worst enemies, for the darkest secret of the House of Doors is that its monstrous creations are inspired by worst nightmares of those trapped inside!