A human-looking alien crash-lands outside the village. Two police officers are terrified and attack him. He kills one by accident in a Gun Struggle and is shot by the other. He stumbles into the bar and collapses. A friendly doctor removes two bullets from his chest and treats his wounds.
While recuperating, the alien introduces himself as Mr. Williams and bonds with Pedro, the orphan boy who sweeps the bar. Williams gives Pedro a gift and says he will explain it later.
The bartender calls the army about the alien, and soldiers and villagers storm the bar. Williams tries to explain that he comes in peace. He tells Pedro to show them the gift, but the villagers take it from the boy and set it on fire. When Williams and Pedro try to reach for each other, the soldiers panic and gun him down until he dies, thinking he was about to harm the boy. The doctor pulls what remains of the gift from the fire. It reads, "Greetings to the people of Earth: We come...in peace. We bring you this gift. The following chemical formula is...a vaccine against all forms of cancer..."
The rest is burned away. The doctor sadly says, "We have not just killed a man; we have killed a dream."
This episode includes examples of the following tropes:
- Aliens in Cardiff: Williams' ship crash-landed in the vicinity of the mountain village of Madeiro, Mexico, just over the border with Texas.
- Aliens Speaking English: Williams speaks perfect English.
- Blind Musician: The guitarist Ignacio is blind.
- Children Are Innocent: Pedro immediately becomes friends with Williams because, as a mistreated orphan with no friends, he can relate to the stranger. Other than the doctor, he is the only person in Madeiro who believes that Williams is no threat to the village.
- Conveniently Interrupted Document: The partially burnt gift is burned away just at the point where the cancer cure appears.
- Cure for Cancer: Williams came to Earth in order to provide humanity with a vaccine against all forms of cancer.
- First Contact: Humanity makes first contact with an alien race in the form of Williams.
- Human Alien: Williams is entirely human in appearance but he has a stronger constitution than the average human. He recovers very quickly from two bullet wounds to the chest. According to the doctor, his pulse is stronger than that of his healthiest patients.
- Humans Are the Real Monsters: Williams is killed by the paranoid and suspicious people of Madeiro, who believe him to be either Satan or a practitioner of Black Magic.
- Innocent Aliens: Williams' goal in coming to Earth, giving humanity a Cure for Cancer, was entirely selfless and honorable.
- No Name Given: The doctor is not named.
- Privacy by Distraction: When he's about to operate on Williams, the doctor sends Pedro out to stargaze.
- Skip the Anesthetic: Williams catches the doctor as he's about to administer ether before operating and insists he not use anesthetic. His pain tolerance exceeds a human's, so it's less necessary.
- Space Whale Aesop: Don't kill aliens and burn their gifts, or you might rob the world of a cancer cure.
- We Come In Peace: Williams tells the mob that he has come to Earth in peace shortly before they kill him. Similarly, the document that he gave to Pedro says, "We come as friends and in peace."
- We Come in Peace Shoot to Kill: Type 1. Williams is peaceful; it's the humans who are aggressive.
- Whole Plot Reference: This episode is a sci-fi version of the story of Jesus. Williams is an alien visitor who has arrived on Earth with a gift for humanity but he is killed and the gift is destroyed. The parallel is made clear when the doctor says that the bartender Manolo, who has told the Mexican Army of Williams' presence, should have been christened "Judas."