Dr. Steven Sorenson plans to tap the geothermal energy of the Earth's interior by means of a thermonuclear device detonated deep within the Earth. This experiment causes a crack to form and grow within the Earth's crust, which threatens to split the earth in two if it is not stopped in time.
| Actor | Role |
|---|---|
 Dana AndrewsDr. Stephen Sorenson | Dr. Stephen Sorenson |
 Janette ScottDr. Maggie Sorenson | Dr. Maggie Sorenson |
 Kieron MooreDr. Ted Rampion | Dr. Ted Rampion |
 Alexander KnoxSir Charles Eggerston | Sir Charles Eggerston |
 Peter DamonJohn Masefield | John Masefield |
| SSydna ScottAngela | Angela |
 Gary LasdunMarkov | Markov |
 John KarlsenDr. Reynolds | Dr. Reynolds |
 Alfred BrownDr. Bill Evans | Dr. Bill Evans |
 Mike SteenSteele | Steele |
 Todd MartinSimpson | Simpson |
| JJim GillenRand | Rand |
| BBen TatarIndian Ambassador | Indian Ambassador |
| EEmilio CarrereNot listed | Not listed |