The exposition of the story is when the banker and the lawyer get into an argument over capital punishment. The banker condones it, while the lawyer prefers life in prison.
This leads to the inciting incident, or the bet itself. The banker wages 2 million rubles against 15 years of the lawyer's life in his garden house, a simulation of life in prison.
The rising action deals with the lawyer's years in prison. The lawyer reads, plays piano, drinks. It also includes the banker's decision to kill the lawyer a day before the bet is over, to blame the murder on the the watchman.
The climax comes on the day before the fifteen years is up, and as the banker intends to kill the lawyer, he sees him asleep with a letter at his table. The letter says that the lawyer renounces humanity and intends to leave the garden house minutes before the bet is over. This is also the anti-climax, as the banker refuses to murder the lawyer and no one wins the bet.
The falling action shows the lawyer indeed leaving minutes before he cashes in on the two million rubles.
The resolution has the banker putting the letter in a safe. Does he do this to prevent himself for being implicated in a crime (reneging on the bet)? Or, does he value the letter more dearly than money? In other words, does the bet teach both the banker and the lawyer to renounce vanity and materialism, to value human relationships?