In the murky depths of Los Angeles' world-famous La Brea Tar Pits there lies an ancient secret - a creature that, awakened by underground construction, turns a night of somber packing for Barry Greenwood and his co-workers into a desperate fight for survival.

First Stop...the Tar Pits, as Gary and Eric investigate the incredible creatures that came after the dinosaurs, from giant ground sloths to savage saber-tooths. It's a trip back to the age of monstrous mammals in this wild and whimsical blast into tour prehistoric past.