Mists of dawn

Dr. Robert Nye, a nuclear physicist working at White Sands Missile Range has finally finished his space-time travel machine after 20 years of research. On the eve of its maiden voyage to Ancient Rome, Dr. Nye's nephew Mark is trapped inside and sent back in time to the year 50,000 BC when a nearby rocket test explosion sends him careening into the controls. When Mark arrives at his destination he must survive the two weeks it takes the space-time machine to recharge for the return trip with nothing but a few matches, a pocket knife, and a 6-shot .45 revolver.