In this episode, it starts off as a calm scene with Courage, Muriel, and Eustace together in the kitchen. Courage then is frightened by a mouse, jumping on top of Eustace's head, causing him to pull out his "Ooga booga booga!" mask, scaring the life out of Courage. Courage then runs out of the house on to the porch, trying to calm himself down. This is when a U.F.O. comes out of nowhere, right in front of the home.
Courage then witnesses the U.F.O. land, dropping off a chicken, which then proceeds to Courage freaking out, rushing into the house before he is seen. He then tries to grab the attention of Eustace and Muriel by telling them what he saw in a sequence of transformations. They rush outside only to find nothing there, causing Eustace to scare Courage once again, Muriel then hitting him with a rolling pin. Courage then runs behind the chicken coop to hide from Eustace, hearing loud noises coming from it while standing there. He then proceeds to see whats happening inside, finding the Space Chicken strangling and killing all of the other regular ones.
Courage, seeing the massacre, runs back to the house to get help from his owners. He runs inside, grabbing Muriel, and takes her inside the coop. All that's inside the coop is the space chicken, with the bodies of all the regular chickens mysteriously gone. While Courage is trying to figure out the wear about of the other chickens, Muriel then proceeds to checking if the space chicken (unknown to her) has laid an egg, finding four eggs, with red spots on them, underneath it. Courage then smacks two of the eggs out of her hand, angering the space chicken. Muriel then leaves right after, Courage left with the space chicken. As he turns to the chicken, he realizes that it's already outside, and has locked him up inside the coop.
As he tries escaping, Muriel is cooking the space chicken's eggs, preparing them for Eustace and herself. Finally after Courage escapes the coop, he starts looking for something in the ground. While this is happening, Eustace has already eaten the eggs, slowly starting to transform into a mutant chicken. Courage finally comes out of the ground with a sling shot, racing back to the house. Muriel witnessing Eustace's transformation, she thankfully stops from picking up the eggs. Courage then hits the space chicken with his sling shot, temporarily knocking it out, but waking immediately, leading to a confrontation (fight!).
The fight fought between Courage and the Space Chicken is then fought in a bunch of different games (checkers, arm wrestling, fencing, etc.). As these two are fighting, Eustace is going through a chicken transformation,slowly becoming a chicken himself, with Muriel freaking out and figuring what to do. Courage eventually beats the chicken at his games, but the chicken pulls out a laser and shoots at Courage, which misses and ends up backfiring on himself. Eustace, in full chicken form, then attempts to attack Muriel, only to be disintegrated by Courage and his laser. With all dangers gone, Muriel and Courage finally get to sit down and relax, but the mouse is eating Eustace Chicken's ashes before slowly turning into a mutant chicken, causing Courage to scream during the iris out. Courage pops out of the closing circle exclaiming, "This shouldn't happen to a dog!", before the circle closes on his nose.
- This episode was almost 4 years before they made Courage the Cowardly Dog into a full series.
- First appearance of Courage, Muriel, Eustace, and Space Chicken.
- Muriel and Eustace do not speak in the episode.
- There are also various pictures of people in real life shown in the episode.
- John R. Dilworth makes a cameo in this episode, appearing on a billboard with the text "Drink Silly Pop!" and getting zapped by the Space Chicken's laser beam.
- The ending where Courage opens the iris and says, "This shouldn't happen to a dog" and then having the iris close on his nose with him saying "Ouch!" is a reference to the ending of the 1944 Bugs Bunny Robert Clampett cartoon Hare Ribbin'.
- This short was nominated for an Academy Award for Best Animated Short Film. It lost to the Wallace and Gromit short A Close Shave.
- This pilot premiered as a What A Cartoon segment.
- It is shown during the VHS release of Scooby-Doo and the Witch's Ghost.