Arthur Chamberlain, an engineer who works in a midtown Manhattan office building called the Metropolitan Tower. When the sun suddenly begins moving backwards in the sky, setting rapidly in the east, he is the only one to realize what is actually happening: a flaw in the rock beneath the building has caused it to subside, but instead of moving in space, the building is falling backwards into the past. When the subsidence finally ends, the building is located several thousand years in the past, and its 2000-odd inhabitants find themselves stranded in pre-Columbian Manhattan!