The Prince and the Pauper

Tom Canty is poor boy who has always dreamed of a better life. One day he meets the Prince of Wales, Edward Tudor. In his excitement the boy comes too close to the prince and almost gets beaten up by the guards. However, Edwards saves the boy and invites him to his chamber. After getting to know each other, they decide to switch their places for some days. The prince dresses as the poor boy and goes on the street, while Tom remains in the castle. Edward, however, does not know what awaits him on these dangerous streets.
Why did the prince save the poor boy? What is the reason for them to switch places? What do they want to achieve with this experiment? How will prince Edward deal with all the obstacles he is going to face? Will the two boys go back to their real lives?
Find all the answers in Mark Twain's novel "The Prince and the Pauper", published in 1881.