"The Bet" has a complicated plot and covers a period of fifteen years, and yet Chekhov brilliantly manages to compress the whole story into just a few pages. He does this by starting close to the climax and providing much necessary exposition in the form of flashbacks in the banker's mind.
Chekhov's main problem is with verisimilitude--making the bet believable. It is actually quite fantastic, something Edgar Allan Poe might have conceived. A young man bets he can spend fifteen years in solitary confinement. An older man bets two million rubles that he will not be able to endure such confinement. The young man stands to gain a fortune, but the older man has nothing to gain--and two million rubles to lose.
In the flashbacks at the beginning of "The Bet," Chekhov takes pains to explain how the bet came to be made. Chekhov begins his flashbacks almost immediately.
The old banker was walking up and down his study and remembering how, fifteen years before, he had given a party one autumn evening.
This is an all-male "stag" party. There must have been a lot of drinking, but Chekhov never mentions liquor because he does not want the bet to seem inspired by drunkenness. He states that there were "many clever men there." Once the banker has bet two million rubles before a number of witnesses--no doubt showing off his great wealth--he is obligated to go through with it as a matter of honor.
The bet arises out of an argument about the death penalty. Some guests argue that the death penalty is more humane that a long prison sentence, while others, including the young lawyer, argue that the most extreme form of punishment should be life imprisonment.
Somehow the banker and the lawyer begin arguing about solitary confinement. The banker remembers the following exchange.
"It's not true! I'll bet you two million you wouldn't stay in solitary confinement for five years."
"If you mean that in earnest," said the young man. "I'll take the bet, but I would stay not five but fifteen years."
Significantly, Chekhov writes:
And this wild, senseless bet was carried out!
The author is attempting to make the bet plausible to the reader by admitting that it is a wild, senseless bet. The banker does not believe he is risking his money because is certain the young lawyer will be unable to endure more than a few years of solitary confinement, even though the lawyer would spend those years in comfort and not be treated like the Count of Monte Cristo or the Man in the Iron Mask.
The second flashback at the beginning of the story begins with:
Then he remembered what followed that evening.
In one long paragraph Chekhov spells out the precise terms of the bet the two men made. The lawyer would be imprisoned in a lodge on the banker's estate. He would have no human contact and could not receive letters or newspapers. However:
He was allowed to have a musical instrument and books, and was allowed to write letters, to drink wine, and to smoke....The agreement provided for every detail and every trifle that would make his imprisonment strictly solitary, and bound the young man to stay there exactly fifteen years, beginning from twelve o'clock of November 14, 1870, and ending at twelve o'clock of November 14, 1885.
These details convince the reader that the bet is made in dead earnest and that one or the other man will have to lose. The question becomes whether the young lawyer--or any man--could stand fifteen years of solitary confinement without going insane.