In the story "The Monkey's Paw" by W.W. Jacobs, the irony, or difference between what the Whites think will happen and what actually happens, is that the monkey's paw, an object of their desires to have wishes fulfilled, becomes a curse rather than a blessing.
This ironic outcome is foreshadowed in the words of Sergeant Major Morris, a guest of the Whites whose demeanor is nervous when he recounts his possession of the monkey's paw which was passed on to him. For instance, he admits to the paw's giving of three wishes, but his face whitens and his teeth tap against the glass from which he drinks; then, he replies to the query as to what the third wish was, "I don't know what the first two were, but the third was for death. That's how I got the paw." Solemnly, he urges the Whites not to keep the paw, but to "let it burn."
Of course, the greed of the Whites supercedes the fear of the magic of the paw. They make a wish for a grand sum of money, a wish they receive; however, ironically, Mr. and Mrs. White lose their son Herbert in the fulfillment of the wish. For, the two hundred pounds is the amount of payment due on the life insurance policy for Herbert, who is killed in an accident at work. In another dramatic ironic twist, the lonely parents wish for their son back, but he returns a mangled, hideous creature; so, Mr. White must wish him dead to spare Herbert and his wife the agony of his living a tortured life.
The irony in "The Monkey's Paw" is situational irony which by definition is:
"Situational irony results from recognizing the oddness or unfairness of a given situation, be it positive or negative. Even though a person typically cannot justifiably explain this unfairness logically, the coincidental nature of the situation is still very obvious to those evaluating it."
The Whites in wishing on the monkey's paw experience an odd unfairness in the way that the wishes are granted. They come out of the experience having less not more.
The Whites go into the realm of the monkey's paw knowing that those who use it are subject to misery. They were warned by Sergeant Major Morris, who himself, is the second owner of the monkey's paw and does not reveal what his experience was like, but he does tell the Whites that the first owners third wish was for death.
It is so ironic that in a situation where a person is expected to gain riches through the use of a a magical talisman, that he actually ends up paying a high price just for wishing. The wishing process which is expected to bring joy actually brings great sorrow.
The kind of irony in "The Monkey's Paw" is dramatic irony. The reader should expect the fact of the Whites having three wishes as something which would bring them good luck and fortune, but the very opposite happens instead. Sometimes this is called situational irony, but the sense is the same: things work out in a completely different way from what is "supposed" to occur.
In this case, the Whites get the money they wished for as a compensation for Herbert's death, and the next two wishes are "spent" on calling him from and putting him back in the grave.
The man who put a spell on the monkey's paw did it because "He wanted to show that fate ruled people's lifes, and that those who interfered with it did so to their sorrow." (Poe,E.) The White's were good and honest hardworking people. They had a fairly good life and needed nothing, but the paw tempted them. They were warned but they could not resist to try and see if they could have some good come of the wishes that the paw possessed.
They wished for two hundred pounds. Their son died in an accident at work and they were awarded the two hundred pounds in compensation for their loss. Now their hearts ached badly in grief. The woman in her grief became reminded that the paw still had two wishes. She wanted her son back. She demanded that the man wish for his return. He wished his son were back.
A knock came to the door and ouside was the creature that was his son come back from the grave. There was but one wish left. His wife wanted her son badly. Before she could open the door the man used his last wish. The son was gone.
The irony in the story is that the people had been happy before and were satisfied with their life until the idea of wishes came about. Each time they wished for something, they were brought something worse. In the end they had lost the child that they most treasured for a mere 200 pounds.
The White's had failed the test of fate by interfering with it. They had altered their lives for the worse.