The short story "The Lumber Room" by Saki tells of a rivalry between Nicholas, a precocious and mischievous boy, and a distant relative who claims to be his aunt. Nicholas refuses to eat his bread and milk, claiming there is a frog in it—which is true, because he put it there himself. As a punishment, the aunt arranges an excursion to the beach for the other children for the sole purpose of depriving Nicholas of the pleasure of going along. It seems she is in the habit of inventing desirable outings mainly to punish children by making them stay at home instead of going.
Once they are alone, the aunt forbids Nicholas from entering the gooseberry garden. Her only motivation seems to be to catch him trying to do it so he'll get into more trouble. He tricks her by pretending to go to the garden, but then heading for the lumber room instead, which he finds much more fascinating.
Meanwhile, the aunt, thinking that Nicholas must have disobeyed her, searches for him in the gooseberry garden and falls into the rainwater tank. Nicholas pretends that when his aunt calls for help, it is really the voice of the devil tempting him to do something he has been forbidden to do. He ignores his aunt's pleas and does not rescue her.
Why does Nicholas refuse to rescue her? He is clever enough to understand that he can use the situation to his advantage. His intention is to get back at the unkind aunt in a way that he cannot be blamed. She forbade him from going into the garden, and she also warned him not to yield to the temptations of the devil. In not rescuing his aunt, he can claim that he was only obeying her. He really does it, though, out of vindictiveness, out of a desire for revenge against the aunt who he perceives is always picking on him. Whether you think he is justified in doing this is a matter of personal opinion.