Gyro Gearloose is working on a satellite dish that will allow him to watch television channels from around the globe. As he prepares to make one more minor adjustment, he gets shocked and then stumbles backwards down the opening in the roof, getting tangled up in the cord and changing the position of the dish. At this point, Gyro's television starts displaying a most peculiar transmission. A mothership piloted by alien ducks has picked up the signal from the dish. The commander believes there are intelligent beings on Earth, and she believes that Gyro can show the way.
Meanwhile, back on Earth, Scrooge is having great difficulty trying to solve a problem: the farms have produced an excess amount of wheat. The farmer tells Scrooge that all the wheat will be left to rot if it remains unsold. Not wanting all the grain to go to waste, Scrooge has the surplus wheat shipped off to his mansion, where he tries (unsuccessfully) to sell it. Webby and the nephews bring in an ant farm, but Scrooge thinks that anything smaller than a penny isn't even worth two cents, as he sets the farm on his desk. It's at this point that Scrooge receives a phone call from Gyro, who tells him that the alien ducks who contacted him are suffering from a food shortage on their home world. Gyro explains that the aliens want all the wheat he can spare, upon which Scrooge agrees and awaits their arrival. While Scrooge talks to Gyro he unknowingly knocks the ant farm over, spilling the ants all over the chair, and gets a sharp nip in the tail end when he sits down.
The mothership launches a spacecraft down to Earth. Gyro is working with Launchpad to mark the place for the aliens to spot. Launchpad offers to glue on the paper while Gyro practices his welcoming speech. Huey, Dewey, and Louie tell their uncle that the aliens are going to land in the backyard and set off to help Gyro keep an eye out for them. Webby, however, is rather upset, as she has found all the ants except one.
While Launchpad is using the glue, a tiny object starts flying around him. Thinking it's some kind of pestering bug, Launchpad swats at it, but ends up falling off the roof and lands in the bushes. The object then flies in through the open window and starts circling around Scrooge. First he tries to swat it, then he tries spraying it, and when it finally lands on his desk, he is about to whack it with a mallet. But Webby enters the room and stops Scrooge before he can do so, and when the nephews examine it more closely, they find out it's the scout ship sent by the mothership. Since the Micro Ducks are about the size of ants, they use a megaphone in order to make their voices heard. The aliens agree to pay with a bunch of gemstones, but since the gems are merely "bits of dust" on Earth, the Micro Ducks use a Molecular Manipulator, which they use to enlarge the gems to a reasonable size. Afterwards, the Micro Ducks use the Manipulator to shrink the excess wheat for transport back home. The Micro Ducks then head for home, but while Scrooge examines the gemstones, he finds that they left the Molecular Manipulator by mistake. He gets the idea to enlarge his first nugget of gold, and uses a pair of tweezers to work the machine. Despite trying to be careful, Scrooge ends up snapping off the lever and ends up shrinking himself and the kids to the Micro Ducks' size.
Since the Manipulator now has a broken lever, the nephews are unable to get it to work. When Gyro enters the room, Scrooge and the kids try to get his attention by shouting, but their voices are far too small to be heard. Believing that he missed the whole show, Gyro decides to head home. Scrooge suggests calling for help, but the ducks are so small, they can't even lift the receiver. Suddenly, Twitchy, the missing ant Webby had been searching for, shows up. But returning to their normal size is the top priority, and so they set out to find Gyro. Scrooge and the kids slide down the phone cord and into the carpet, but Duckworth, who is vacuuming, unknowingly sucks up the lot of them. Duckworth then empties the vacuum bag into the trash can, and then the garbage men come along and empty the can into their truck. The truck drives all the way downtown, and when it stops at a red light, Scrooge and the kids escape by drifting away on a dandelion.
Shortly after the shrunken ducks land on the curb, a passing street sweeper floods the roads. The ducks scamper away and hitch a ride on a box of matches as the water sweeps the box away. They use the matchbox as a life raft, avoiding obstacles before being swept down a storm drain and into the sewers. The ducks get off the matchbox by a ladder leading up to a manhole cover, but are confronted by a pair of sewer rats. Scrooge strikes a match, lights the whole box, and then sends it toward the rats, who flee in terror.
The shrunken ducks then climb out of the holes in the manhole cover, but a passing vehicle nearly flattens them. The ducks just manage to reach the sidewalk before they are run over. Webby states that they need a ride to get to Gyro's place faster, and she spots a skateboard. The ducks climb onto the skateboard, and the skater rides the board all the way to the park. However, when the skater gets to the bottom of a downhill slope, he recklessly ends up running into some passing cyclists. The skater dodges the cyclists, but is now off balance, and his skateboard ends up crashing into a "Keep off the grass" sign. The shrunken ducks fly through the air, and while Scrooge and the nephews land safely on the ground, Webby ends up getting caught in a web. The spider who lives there crawls toward the girl, but the others manage to pull her free before she gets eaten.
After wandering around for what seems like a long time, Scrooge and the kids are finally tuckered out. Webby is starting to get frightened, and the group needs to find a way out of the park. Suddenly, fluffy kernels of popcorn start coming down, which means that someone on the park bench is feeding pigeons. The nephews pull a piece of string from a trash can and drape it over a popcorn kernel just as a passing pigeon eats it. Everyone climbs onto the pigeon's back, and they use the string to steer her towards Gyro's barn. After the pigeon lands on the roof, the ducks dismount her, and she flies away. Since it's a long drop to the ground with a high chance of injury, the group uses one of the pigeon's discarded feathers to float down safely to the foot of the front door. Once the ducks enter the place, they find Gyro snoozing away in his easy chair. Scrooge decides to give Gyro a "poke to the nose" to wake him up, but the nephews decide Gyro's alarm clock will be much quicker. As Scrooge is trying to get Gyro to wake up, the nephews pull the alarm switch, setting off the clock. Gyro suddenly snaps awake, and Scrooge flies right through the air and into a glass of water on the side table. Gyro shuts the alarm off, picks up the glass, and starts drinking from it. Just as Scrooge is about to get washed down Gyro's gullet, Gyro suddenly notices him and realizes why he was unable to find Mr. McDuck.
Gyro then heads over to Scrooge's Mansion in his hovercraft, with the shrunken ducks riding on top of his hat. But it just so happens that the Micro Ducks have returned to Scrooge's office and have just now finished repairing the Molecular Manipulator. The aliens board their spacecraft, taking the machine with them. Just as the aliens take off, Gyro enters the office, with a magnifying glass to try and find the machine. But when Gyro examines the desk, Scrooge and the kids find out that the aliens have already been here and are about halfway back to their homeworld. Webby starts sobbing at the thought of remaining small forever, but Scrooge assures her that they'll get back to normal somehow. Gyro feels depressed, thinking he'll never have the opportunity to meet aliens in person. Just then, Launchpad emerges from the bushes outside the window, wrapped in paper coated with glue. When Gyro examines Launchpad's forehead, he notices a tiny red object and finds out that the Micro Ducks have ended up getting stuck to the paper.
Once their spacecraft has gotten unstuck, the Micro Ducks use the Molecular Manipulator to restore Scrooge and the kids to their proper sizes. The ducks cheer, and the aliens head for home shortly afterwards. Later that day, Scrooge is examining one of the gemstones the Micro Ducks had paid him for the wheat, when Duckworth comes in carrying a tray with tea and sugar. As Scrooge takes another look through the magnifying glass, he notices Twitchy the ant walking on his desk. But instead of squashing the ant, Scrooge instead gives Twitchy a cube of sugar. As Twitchy starts snacking away on the cube, Scrooge tells him it'll be their little secret.
- Tress MacNeille as Commander
- Terry McGovern as Launchpad McQuack
- Will Ryan as Additional Voices
- Hal Smith as Gyro Gearloose
- Russi Taylor as Huey, Dewey, and Louie, Webby Vanderquack
- Alan Young as Scrooge McDuck
- DuckTales: Space Invaders
- DuckTales: Raiders of the Lost Harp / Space Invaders
- DuckTales: Volume 1