Day: Steve and Fitzhugh, carrying a wire plug, hide at a fire hydrant from a giant policeman numbered 778 (Chip Morton). They cross a street, leaving the wire and hide in an abandoned storm drain. 778 reports this to a Dr. Kraal (Mr. Farnum) who wants the humans caught unharmed. Steve finds an exit right into the forest but it is blocked by rocks. The two men find an electric conduit plugged into the city main. Following it, leads them to a switch. Fitzhugh warns him not to throw it. Steve says, "Isn't that what switches are for?" When Steve throws it, they find themselves in a well lit computer complex--all Earth sized instrumentation.
Fitzhugh and Steve look around the complex and hear Shepard Space Center in Brookside, Kentucky trying to contact 275 Exploration Team. Captain Ashim of the secret police and Kraal hear Steve try to contact the center back. Three years ago one little man escaped from them. Others of his group died under Kraal's experimentation with new methods--rather than tell Kraal about where the complex was. It almost cost both of them their jobs. Steve leaves to bring Mark back--warning Fitz not to try anything with the radio until he gets back with Wilson. They can receive but not send. Steve suspects it may be an elaborate giant hoax--a trap. He uses thrown rocks to avoid giant policemen searching for the transmitter---which Fitzhugh makes easier for the giants by sending messages against Steve's order. In Spindrift, they hear him. Steve calls him an idiot. Mark scrambles the message Fitz sends. He asks Barry for a portable jammer which Barry gets, "Here, Mr. Wilson." Mark then turns the walkie talkies into portable transmitter jammers which the girls and Barry spread out through the forest--so as not to lead the giants to the spaceship---which if not jammed, they would find. Ashim was almost fired when Kraal killed the former group of Earth people. Kraal refers to the any little person as "it" and doesn't really see it a crime if one or two of them die. Fitz finds a decayed body in the complex behind a console--he followed a microphone wire to it. He runs out into the daylight into Steve and Mark who usher him back inside. Using the wire, Mark finds a recording the dead man made, telling them about a 2 minute destruct level and recognizes some of the equipment, components of which as having been built in one of his own plants. 275 was caught in the same space warp Spindrift was. Fitzhugh and Steve dig through the dirt exit into the forest. Steve tells the others, Valerie telling him that at first the sound of the squealing was making her climb the trees but now she is starting to like it--it may mean a rescue party will be able to find them and get off this world. Steve alerts the others, finding Dan with a hurt shoulder which he hurt while running away from a security officer. One comes at them as they talk, taking them unaware! Suddenly, the spot him, towering over.
Steve diverts the giant for Dan to get away but is caught himself. Dan alerts a worried, caring Val, who asks too many questions for his liking. Steve tells Ashim he knows Ashim could crush him if he doesn't answer his questions--which he won't. Ashim then acts nicer, wanting only the transmitter. "I'm not telling you that," Steve insists. Dan gets Mark to go to Steve while Fitzhugh plays nursemaid to Dan's dislocated shoulder as an excuse to remain behind. Kraal tests his foam invention on a tough convict who tells them everything truthfully without straps on his chair to hold him in. He was planning to kill the guard with a hidden tool he made and escape. Kraal sprays some on Steve who falls against the books on Ashim's desk. The convict falls off the chair...and dies from the foam.
Ashim leaves to wash some of the foam off his hands while Kraal supervises the removal of the dead convict. Mark, without any help from a brainwashed Steve, climbs up to him and tells him to tell Ashim the other members of his group are in the basement ready to blow up the security building. Ashim leaves again to check on this and Mark gets Steve down, talking to him harshly and warning him not to give him any trouble. Steve remains passive and does whatever Mark says. Mark makes him wipe the foam off himself. Ashim returns and finds the pin and rope. Steve comes back to normal and the pair of men escape the building to a the drain area. Kraal tells Ashim if the foam is wiped off after a few minutes of being sprayed--it is harmless. Steve thanks Mark, touching his shoulder. Fitzhugh takes Dan's place in the woods at the radio jamming but Kraal sprays him with the foam, Ashim at Kraal's side. Fitzhugh begins to show the giants where the complex is.
Steve tells Val to get Betty and Barry and go back to the ship and to forget the jamming. She obeys, "You're the boss." Steve gets back to the complex, just as Mark makes contact with the Space Center but needs 5 minutes more. Steve tells them they haven't the time, "The giants used the foam on Fitzhugh." He moves for the destruct lever and has an all out fight with Mark. Steve even throws Dan to the floor when Dan interferes, siding with Mark. Machines blow up and spark during their fight. Steve hits the switch just as Kraal finds the place and begins filling the complex with foam. Ashim has had his men block off all the other exits as to Fitzhugh's instructions. Kraal and Ashim order Fitzhugh to wipe the foam off himself. Steve, Mark, and Dan find both ways out blocked. Foam fills the corridors. Steve tells the two men, "Back to the complex and don't let that foam touch you--it's a killer!" Massive amounts of the stuff flood them in; Dan and Mark telling Steve, "There's no way out." Steve looks, "Then we'll make a way out! Start digging." They grab shovels to dig a way out the roof on a small hill. Above Ashim muses to Kraal, "In a year or so we may even find a way to reach the planet of these little people. They may be small but they must be rich beyond our dreams." Ashim's foot caves into the weak area of the ground...the three men see it lower at them. Steve yells, "Grab on! Quick!" The trio ride up on his foot as Kraal helps Ashim pull it out and up. Just then the entire complex blows up.
The blasts kill Ashim and Kraal but the four Earth men survive. Helping Fitzhugh, Steve says, "You see, sometimes it pays to be small."