This time, the X-Venture Xplorers are in the Permian - Carboniferous eras, around 350 million years back. Many creatures which are small today were very big back then- which presents a big problem when the X-Venture Xplorers come face to face with things like giant spiders! Even more big dangers from today's small creatures await the team as they quickly realize that it is a bad idea to be PLAYING IN THE PERMIAN!