With the cyclotram, an atomic-powered rock-boring vehicle, Dr. Jerimiah Morley leads an expedition into a subterranean world.
Bruce Kellogg
as Wright Thompson, Jr.
Otto Waldis
as Dr. Max A. Bauer
Jim Bannon
as Andrew "Andy" Ostergaard
Tom Handley
as Dr. James Paxton
Dick Cogan
as Dr. George Coleman
George Baxter
as Carlisle Foundation Chairman
Marilyn Nash
as Dr. Joan Lindsey
Victor Kilian
as Dr. Jeremiah Morley (uncredited)