At the KXKVI radio station, Gene Maxwell is DJing when his sister-in-law Caroline comes in with paperwork. Gene tells her to call in her husband Allan, because they're losing broadcast power again. Caroline says that Allan is in the transmitter shed and he cut down the power on purpose. When Gene points out that it's against the law, Caroline says that Allan has been stealing power--and equipment--for weeks. Allan won't open the door, and Gene has her call Allan.
In the shed, Allan is bringing in a signal when the phone rings. He answers it, tells Caroline to come over because he wants her to see it, and immediately hangs up. Caroline goes to humor her husband and assures gene that he'll be ready to go to the testimonial that night. Allan calls her in when she knocks and shows her the transmission signal on the V monitor. He says that he thought it was hydrogen static at first, but there's a high-pitched noise that he can't identify. Allan says that it's coming from outer space but hasn't been able to pinpoint it yet. Caroline warns that he's cut the station power in half, and warns that they could lose their sponsor. Allan insists that it's more important and says that the bills will be paid, and explains that the monitor is three-dimensional and he's able to make the signal solid.
His wife wonders what good it is, and Allan says that it's interesting and important. He admits that he's a nobody, but it's nobodies who make the big discoveries. Caroline says that every day it takes him away from her location, but the signal more and more, until she hardly knows him. She warns that his friends want to honor him, but Allan insists that he doesn't have time for it. Angry, Caroline says that the signal is cold and she doesn't like it. She reminds him of the testimonial to honor him that night. Allan says that he'll try to remember it, and vaguely promises that he'll be ready on time.
Once Caroline leaves, the power flickers and a humanoid image appears in the monitor. It solidifies into an alien creature, and Allan speaks to it through the microphone. The Being looks around but doesn't respond, and Allan holds up a star chart and shows it Earth's location. He tells it to translate its binary impulses into his computer, and Allan draws on more power to power the computer to translate. The Being speaks, asking Allan who he is, and he identifies himself. It identifies its location in the Greater Andromeda Galaxy, and confirms that it can barely see Allan. The Being says that it's breaking the rules of its people by using the equipment for exploration, and Allan admits that he is as well. They discuss their physiological differences since the Being has no nose or mouth, and it explains that they are nitrogen-based lifeforms. The nitrogen-based creatures do not have death in their dimension, and they are not allowed to contact Earth because it practices war and is too dangerous. Allan asks if they have God, and the Being says that electromagnetic forces underlie all things, and energy and matter are the same.
Later, substitute announcer Eddie Phillips pulls up to Caroline outside the station. He says that he has some records to the station, and Caroline sends him to talk to Gene. She then knocks on the shed door, and Allan looks out. He says that he can't go to the testimonial because something major has happened and he has to write out a report. Caroline doesn't want to hear or see about his discovery, and Allan warns that one hour could make all the difference in the world. She tells her husband that she's bringing everyone there to see his workshop, and Allan gives in and says that he'll be there.
Gene shows Eddie the booth and tells him to ignore the needle showing the power fluctuations. Caroline comes in to get Eddie and says that Allan will follow them in his station wagon.
Allan tells the Being that he has to go, but asks it to keep the channel open. It warns that it is dangerous, but Allan insists and says that he'll be back in one hour. The Being tells it not to change the power levels, but Allan assures him that the selectors are locked. He goes to the booth and checks the settings, and Eddie says that Lee and Caroline have already left. Allan tells Eddie to leave the settings where they are and to keep the needle where it is. Eddie confirms what knob will boost the power, and asks how far they could carry a signal at full power. Allan tells him not to touch it and leaves.
At the testimonial, the mayor presents Allan with is plaque. Afterward during the dance, Allan tells Caroline that he might as well leave because no one has even noticed him. His wife points out that no one knows who he is because he's been in seclusion so long, and warns that if he leaves her then she'll leave him. Meanwhile, Gene leaves with a woman, Loreen, and takes her to his car. He turns on the radio and they kiss.
Eddie is on the phone talking to his girlfriend, and says that the power is down but he's going to crank it up so everyone hears him. He hangs up and boosts the power to maximum.
In the shed, the monitor explodes and the Being materializes. It walks out and approaches the main building, smashing in through the booth window.
When the radio station goes off the air, Gene realizes that something is wrong and goes to tell Allan. Allan runs to Gene's car and realizes that the station is over-range and Eddie said something about welcoming new listeners in Canada. Realizing what has happen, Allan goes back inside and calls the station. There's no answer, and Allan warns Gene that it's dangerous.
The Being walks to the road and some men passing in a car see it. They lose control and crash, and he Being continues on.
Allan calls Collins at the warehouse to have him run a message over. At the warehouse, Collins looks up as the lights flicker. The phone rings but Collins sees the Being, grabs a gun, and opens fire. The energy omitted from the Being overwhelms Collins, knocking him out.
When there's no answer, Allan goes back to the car and tells Gene that he's going back to the station.
The Being enters town and walks down the streets.
Two policemen arrive at the warehouse and Collins staggers over to them, unable to speak.
People see the Being and run in terror.
Allan arrives at the warehouse and realizes that Collins is in no condition to talk. He drives into town.
The Being breaks into a pawn shop and looks around, trying to make sense of the world around it. It leaves out the back and continues on.
Gene tries to reassure Caroline, but she's furious that Allan has left her. Outside, Allan pulls up and goes inside to find Caroline. He says that something has happened and asks her to come with hi. A woman runs in screaming and Allan and Caroline run to the door as the Being enters. Caroline passes out, and Allan realizes that the Being is emitting radiation. He tells it to follow him back to the transmitter and carries Caroline out.
When the police arrive, Gene tells them what happened. They assume that the Being captured Allan and Caroline, and Gene's hands are badly burned from the radiation. The police receive word of the crashed car, and the head officer asks for reinforcements from the National Guard. When Gene says that Allan was heading back to the transmitted, they drive out.
Allan leads the Being back to the shed and sets Caroline down. he reassures the Being that everything will be all right as Caroline wakes up. She sees the Being and screams in terror, and Allan tells her that the Being is an intelligent being like themselves and he has to send it back. Once Allan hooks up a loudspeaker to the computer, the Being explains what happened. It says that is people know it has broken the law and they will destroy it.
The police pull up outside with Gene and enter the main building. They find Eddie's corpse.
The Being warns that Allan's people are coming closer.
The National Guard arrives and Allan tells Caroline to tell them that it's all right. When she goes to the door, the soldiers open fire and wound her. Allan carries her back inside and the Being says that it can stop the damage by cauterizing the wound with its radiation and stop death. It does so, saving Caroline's life, Allan runs to the door and tells the soldiers not to fire, but the major in charge tells the police to get him out and then they'll open fire. Addressing the soldiers over the loudspeaker, Allan says that the Being saved Caroline's life. The Being comes out and the soldiers open fire.
The Being tells them to stop, and says that they must not use force. It warns that there are powers in the universe beyond anything that they know, and then looks up at the transmitter. It destroys the transmitter and tells the humans that there is much they must learn. The Being tells them to go home and give thought to the mysteries of the universe, and it will leave them in peace.
Everyone leaves, and the Being reenters the shed. Allan follows it in and the Being says that it will disintegrate itself. It doesn't know what waits for it, says, "End of transmission," and disappears.