What is the main conflict in Flatland by Edwin Abbott?

In the hierarchal two dimensional world known as Flatland, the Polygon class rules but this isn’t their story. Rather A. Square adventures out from his two dimensional home to other lands with varying number of dimensions in his exploration of Spaceland, Lineland and Pointland. But his radical thoughts on a land with four
dimensions get him thrown out of the freest thinking land in this satirical novella by Edwin Abott Abott.