Standing well away from the army search, Dr. Blake and young David are suddenly sucked underground. They are captured by two tall, slit-eyed green humanoids and taken via tunnels to the flying saucer. Army troops locate and blow open an entrance to the tunnels, and Colonel Fielding and a small detachment make their way to the saucer entrance. Inside, they confront the Martian mastermind: It has a giant green head with a humanoid face atop a small, green partial torso with several green arm-tentacles, and is encased in a transparent sphere. The Martian is served by the tall, green, silent, synthetic mutants. Under their master's mental commands, the mute humanoids have implanted mind-control crystals at the base of the skull of their kidnapped victims, forcing them to attempt sabotage at an atomic rocket project being built at a military plant near the town; if they are caught, the mind control devices explode, causing a fatal cerebral hemorrhage. The troops and Colonel Fielding, with Dr. Blake and David in tow, open fire on the pursuing mutants as their group escapes the saucer. After a short running battle in the tunnels, they return to the surface. Orders are given for everyone to quickly leave the area: Fielding's troops have planted timed explosive charges aboard the saucer. David runs downhill away from the sandpit, and artillery opens fire on the sandpit, as the charges ticking timer slowly approaches zero.