After Courage sees a list of missing dogs, a flashback appears showing how Courage's parents got sent into outer space by an evil veterinarian. Muriel and Eustace take Courage to the same veterinarian to get him checked out. But the veterinarian also attempts to send Courage into outer space.
One day, Courage notices a missing dog ad on the back of a milk carton. We are thrown into a series of flashbacks on how Courage was abandoned as a puppy. He had two parents that loved him very much, and one day, he got his head stuck in two gate posts. His parents took him to the vet where the creepy, estranged veterinarian frees Courage and then asks to talk with his parents privately. Courage just manages to watch his parents get nabbed by a net and taken away. Courage follows the evil veterinarian and discovers the vet is a mad scientist working on an experiment involving sending dogs up into space and breeding them in space. The vet even created the rocket with his secret knowledge of rocket science and aerospace engineering to send the dogs into space.
Little Courage attempted to save his parents, but is chased down a garbage chute by the vet and he watches as his parents are blasted into space. And that was when Muriel found him and took him home. As Courage remembers all of this, he goes into such a daze even Eustace's "OOGA BOOGA BOOGA!" mask doesn't snap him out of it. Worried, and Muriel and a reluctant Eustace take him to the same evil vet that blasted Courage's parents into space years before! The vet attempts to commit the same evil deed once again, but Courage escapes and is pursued through the hospital by the mad doctor. He is eventually captured and taken to the vet's laboratory. Eustace and Muriel arrive just in time to rescue Courage, but the cruel veterinarian decides that he can't allow his operation and research to be discovered and compromised to the public, and he explains his evil plan to send dogs into space and to breed them into superdogs (based on a poster he saw); they get thrown into the rocket as well. Courage escapes and is chased around the lab. Courage knocks over a bucket of bolts and screws, causing the mad scientist to slip. He tries to open the door to the rocket, but to no avail. As the vet nabs him again, Courage screams as loud as he can into the vet's stethoscope. Courage then grabs the key, unlocks the door and saves Eustace and Muriel and then manages to trap the evil doctor inside the rocket. He hurries to his owners as the countdown counts to T-0 seconds. As it does so, the rocket engines underneath ignites and the rocket lifts off, blasting the evil vet into space.
The episode ends with Courage and Muriel sitting on the porch, with the dog being happy to have her as Muriel wonders of the evil vet's fate and Courage growls at the mention of him. In space, the evil vet's rocket crash lands on a planet, where he finds himself surrounded by all the dogs that he blasted into space, including Courage's parents, meaning that his experiment involving sending dogs up into space and breeding them in space has failed. He is scared as he is caught in a net and is seriously beaten (most likely killed) unmercifully by the dogs off-screen for his actions.
- This episode is one of, if not the, most important episodes of the series as the secrets behind Courage's past finally come to light and how he came to be the dog he is today is explained.
- This episode reveals more about Courage's past, how he lost his parents and how he was adopted by Muriel.
- First and only appearances of the Cruel Veterinarian and Courage's parents.
- This episode marks the only time in the entire series where Eustace's mask fails to scare Courage.
- This episode is the series finale alongside with Perfect.