Undersea Kingdom

Using an experimental deep-diving submarine, a group of adventurers accidentally discover the lost undersea kingdom of Atlantis.

The explorers from surface world find themselves caught up in a civil war between the forces of the righteous Atlantean high priest Sharad and the villainous rebel Unga Khan.

Lieutenant Corrigan tries to rescue his friends from the villainous Unga Khna, but Khan has a dastardly plan to coerce Professor Norton's cooperation through brainwashing.

After saving Sharad's life, Lieutenant Corrigan is given command of the Atlantean army. But Unga Khan's troops are closing in on the city, forcing the Atlanteans to fight for their very existence.

Lieutenant Corrigan and Moloch attempt to infiltrate Unga Khan's headquarters and rescue their friends.

Lieutenant Corrigan tries to get Billy, Diana and Professor Norton out of Unga Khan's headquarters. But the rescue may be foiled by the brainwashed Norton, who thinks that Khan is his master.

Lieutenant Corrigan must stop Unga Khan's troops from laying their hands on the priming powder necessary for Khan's plan to attack the surface world.

Captured by Unga Khan's forces, Lieutenant Corrigan must find a way to stop the completion of Professor Norton's rocket engines.

Lieutenant Corrigan once more attempts to rescue the brainwashed Professor Norton from Unga Khan's captivity.

Unga Khan marshals his forces for the complete destruction of Atlantis.

Despite the wholesale destruction of Atlantis, Lieutenant Corrigan must try to stop Unga Khan from finalizing his preparations for an attack on the surface world.

Despite all attempts to stop him, Unga Khan launches his tower fortress towards the surface world. But Lieutenant Corrigan is on hand to make sure that Khan gets a warm reception from the U.S. Navy.