When the story opens, the entire town of a Martian colony is awaiting the arrival of a rocket ship which is supposed to bring a white man to the planet. The entire population on Mars consists of black people; the youngest members of the society have never seen a white person and cannot fathom what one might look like. Hattie and Willie are the main characters in the story, and Willie emerges as leader in the town. He reminds his wife of all the trouble white people caused their race on earth and how they even hung Willie's father and shot his mother. Willie wants revenge.
He leads a mission around the town, recreating much of the scene black people in America faced before leaving for Mars. The townspeople designate a "whites only" section in the back of streetcars. They rope off sections in the theater for white people. They hang signs declaring the right to refuse to serve customers at any time. They pass quick laws against "intermarriage." And then Willie and the townspeople stand back to await the arrival of white people with guns and ropes.
To their surprise, the white man who emerges doesn't come with ambition to overtake Martian world. Instead, he is humble and defeated. He tells them that the war that emerged after black people departed Earth utterly destroyed every city and town. Large cities, small towns, factories, and farmland lay in waste. As he speaks, the people begin to remember with fondness their local hometowns and the beautiful memories they have left behind there. They connect with both the Earth which they have held in contempt and the white man who stands in defeat before them.
He doesn't seek to overtake Mars. Instead, he offers to work for them, doing all the tasks black people were once limited to prior to their departure from Earth. He offers for the white people to cook meals, shine shoes, work fields, and generally humbles themselves for service to the black population.
This spirit of humility softens Willie's anger, and he realizes that there is "nothing left to hate." Willie therefore drops his own rope, and the other townspeople speed around the town, taking down the signs of hate and discrimination that they had erected only moments before. Hattie declares that this is a new start for everyone, and Willie believes that on this day, he has truly seen the white man for the first time.