The story is mostly about how two kidnappers did what?

"The Ransom of Red Chief" is an early example of what in Hollywood is called a "Busted Caper" story. A criminal, or two partners, or a whole group of criminals plan to commit a crime and something goes wrong which results to their downfall. In O. Henry's story, the kidnappers, Sam and Bill, are making the mistake of moving into a type of crime with which they have no previous experience. They are obviously con artists. They want the ransom money in order to perpetrate another of the kind of swindles with which they are familiar. But in order to get the money to work the "fraudulent town-lot scheme," they have to execute another crime successfully. They may think their biggest problem as kidnappers will be in dealing with the boy's father, but it turns out that the real problem is dealing with the boy himself.

The story is treated comically. Red Chief turns out to be more than they can handle. He loves being kidnapped and loves playing Indian, sleeping on the ground, cooking over an open fire, and never having to go to school. There are several reasons why Sam and Bill can't handle their victim, even though he is only ten years old. One reason is simply that they have had no experience in dealing with children, especially with rambunctious small boys. Another reason is that they can't use physical force. If they were violent with Red Chief they would make him a dangerous enemy. Once they returned him to his father he would be able to identify his kidnappers and tell a lot about them. In many cases of kidnapping children, the victim is murdered to prevent the child from giving information about the criminals and also to prevent the child from testifying against them when they get caught. Sam and Bill obviously are not killers. But if they returned the boy to his father with bruises and abrasions they would make dangerous enemies of both Red Chief and his father. Furthermore, once they become kidnappers they lose any moral authority they might possess as adults--and Red Chief knows it! How can they ask him to behave when they are misbehaving so flagrantly themselves? 

'You know, Sam,' says Bill, 'I've stood by you without batting an eye in earthquakes, fire and flood--in poker games, dynamite outrages, police raids, train robberies and cyclones. I never lost my nerve yet till we kidnapped that two-legged skyrocket of a kid. He's got me going. You won't leave me long with him, will you, Sam?'

In a busted-caper story things go from bad to worse, and the criminals can't just walk away from the mess they have made. What seems like a simple crime turns into a very complicated one. An excellent example of a busted-caper movie is Fargo (1996), starring William H. Macy as Jerry Lundegaard, who hires two freakish characters to kidnap his wife. In the end the wife is dead, her father, who was supposed to pay a million dollars ransom, has been shot dead, one of the kidnappers has murdered the other, an innocent park-lot attendant has been killed, and Jerry Lundegaard is captured and will undoubtedly get a death sentence. Like Sam and Bill in the O. Henry story, the problem is inexperience and incompetence.

Sam and Bill use a lot of big words and malapropisms in their dialogue, but they are really ignorant men and not overly bright. If they were intelligent they wouldn't be down to their last six hundred dollars at their time of life. They find it is easy to kidnap Red Chief and easy to keep him a hostage, but it is hard to get rid of him. The father refuses to pay the fifteen-hundred dollars they demand and offers to take the hellcat off their hands if they pay him two hundred and fifty dollars. They have to trick the kid in order to get him to go home.