The remains of two of the largest predatory mammals of North America are discovered in a cave in Wyoming. The first is a 750-pound Mega-Lion and the second is an eleven foot tall bear equipped with huge claws and muscles. How could an ecosystem support two predators of such size and raw power? Using evidence collected in the cave and studying the skeletal design of each combatant, experts are able to recreate a blow by blow account of how these two ice aged monsters fought to the death.