Hollow Earth Expedition: New Rome

A group of heroes, scholars, spies, and thrill seekers converge at a hangar to examine a wondrous drilling machine. When the group is attacked by a horde of masked gunmen, the group escapes in the machine, drilling down into the Hollow Earth. There, they find themselves in a strange city state ruled by intelligent apes and chimps, and where humans are the slaves. Can our heroes escape the arena and find a way back home?