Four men. Four Days. For the fight of their lives. It was just a walk in the desert to a place 100,000 years in the past. They thought they knew what to expect but they were wrong. Now a team of scientists is trapped in a world they were not prepared for and can never return from. Their only hope lies in a quartet of former US Army Rangers willing to travel to prehistoric Nevada and face unknown horrors and impossible odds to bring them home from Bad Times.