What is the main conflict in Uglies by Scott Westerfeld?

In this novel, Tally cannot wait until her birthday when she will be turned pretty and allowed to live in New Pretty Town with her best friend Peris from childhood. However, when Tally's new friend, Shay, runs away, Tally is told by Special Circumstances that she will remain ugly all her life unless she agrees to track down Shay and bring her back. Uglies is a novel that questions the idea of social pressure to be beautiful and the quest of young people to conform to one specific idea of normal.