The ending is not so startling in these days of DVD. Unlike the original broadcasts, we get to see what the title of the episode is, and in this case, it kind of gives things away.
The story does have some interesting points. It shows the cold, ruthless attitude of the Mexican upper-class to those who worked for them. Technically, the peons were not slaves, but they might just as well have been, and were treated with less consideration than would be shown to livestock.
The opening is a shock, with Paladin coming across a handsome young boy buried up to his neck near an anthill. (Paladin faced such a fate himself once--it appears to be a popular form of execution south of the border.) The man who buried the boy shows up and attempts to prevent Paladin from freeing him. There's no clear explanation of why the boy is to suffer such an agonizing death. Even if there had been, Paladin would never have tolerated such savagery. The Good Samaritan, however, is nonplussed when the rescued victim spits in his face (figuratively speaking), taking his gun and his horse (and a cigar) and leaving Paladin to walk to the nearest shelter.
Arriving at the hacienda of the man who hired him, Paladin finds that the man who had buried the boy is Don Ortega's foreman. The boy, Doroteo, has been getting ideas above his station and is starting to cause trouble. Ortega had hired Paladin to take his daughter Soledad out of the area until the tense situation has been dealt with. Paladin, who had started to give up on the whole situation, is persuaded to stay. Later that night, the boy is let into the hacienda's grounds by his friends. He's come to return Paladin's property, and escapes into the night--not, however, before seeing the foreman killed by another of his friends.
It's decided that Paladin and Soledad should get underway at once. Soledad is disguised (sort of) as a boy.
This part of the plot was the really entertaining bit. It's interesting to compare this episode with the second season "Juliet". In that episode, Juliet had seen far too much death and destruction, causing her to grow up fast in that regard, but was rather ignorant in the ways of men and women. Soledad is quite the opposite. As a well-born child, she's been raised to think of the peons serving her as something less than human, and she has no grasp of the seriousness of the situation, with the resentments of the servant class building up to an explosive point. It's all just a fun adventure. On the other hand, unlike Juliet, she is fully aware of the power she has over men, and practices it at every opportunity. Doroteo had been one of the men she practiced on, with no thought of his feelings on the matter. Paladin treats Soledad quite differently from Juliet, although they were in a life-or-death situation in both episodes. He gets rather exasperated with Juliet, even as he's treating her with kid gloves. However, he's amused with Soledad's capricious attitude. After telling him that she will kill herself if he touches her, she promptly makes a play for him, and gets annoyed when he declines. He has no compunction about teasing her. After listening to her attempts to be provocative, he tells her to come close. Soledad happily snuggles in and waits for a kiss, only to be told that he could not touch her because she would surely kill herself. Paladin strolls away, leaving the brat seething.
Doroteo turns up again, having previously permitted Paladin to escape out of gratitude for his rescue. However, they are now even, and he is determined to take Soledad for himself. Soledad, at first infuriated by their capture, quickly becomes fascinated at the thought of these men fighting for their freedom. Paladin points out that it's her class, which includes her father, that they are fighting against. Soledad is forced to grow up quick when she realizes that he wants her, not for herself, but as a symbol of revenge against her father.
Doroteo and his men are still in the very early stage of their revolution--Paladin rather easily gets control of the situation and they ride off with Doroteo as hostage. Paladin has no particular grudge against the boy, and, once assured that he can get Soledad to safety, drops him off to return to his men. Doroteo boasts that they will hear of him again, that he will become a famous man. So he will. Somewhere along the line, Soledad had learned that his men had nicknamed the boy Pancho Villa, and she casually drops the name as she and Paladin ride off, leaving the viewer to gasp in shock--or not.