After noted explorer Edward Dennison (Peter Fonda, 3:10 to Yuma) vanishes, a search party led by anthropologist Jonathan Brock (Ricky Schroder, 24) embarks on a mission to find him. Retracing Dennison's last known tracks through a secret passage in Alaska - a gateway to the very center of the Earth - the team discovers an underworld tribe of primitive warriors and prehistoric dangers previously unknown to civilization.