The Pied Piper of Hamelin

The Pied Piper of Hamelin is the legend of a town overrun with rats. The townspeople were desperate to get rid of the infestation, as the rodents were getting into their food and homes, and everyone was extremely upset by it.
A piper shows up at the town, stating that he has a solution for their rat problem - at a hefty price. He offers to play his music to lure the rats to their watery grave at the nearby river, for a large sum of money.
Once the deed is done, the Pied Piper is shocked and angered to find that the Mayor of Hamelin has suddenly had a change of heart, and is only willing to pay him a meagre fifty guilders, instead of the thousand that he'd been promised before. The Pied Piper vows revenge on the townspeople of Hamelin.