Mr. Hobson, an American security specialist, reports that an enemy radio transmitter in Mexico has broken down. Since his men have broken the enemy's code, they want the transmitter repaired as soon as possible so they can continue to monitor the broadcasts. Captain Midnight and Icky volunteer to travel to the remote mountain area where the transmitter is located posing as fix-it men in hopes of being hired to repair the broken equipment - and do some poking around in the enemy's base on the side.
Noted scientist Dr. J. P. Hartley has been kidnapped by foreign agents. Captain Midnight, Ikky, and Tut determine he'd been working with extreme cold to make a metal that could withstand practically anything. An ice sheet in the desert tips the guys off to the doctor's location. As Captain Midnight tries to revive the frozen scientist in the spies' icy lair, the military drops an atomic bomb nearby at the government's atomic testing grounds.