From the book jacket:
There was only one way for Chester to do things - his own way. Wilson did things the same way; they were best friends. From double-knotting their shoes to cutting their sandwiches diagonally, Chester and Wilson were two of a kind. "They really are two peas in a pod," said Chester's mother. "Looks like it," said Chester's father. From morning to night - and in every way - they were inseparable. But then they met Lilly... and extraordinary things happened to their friendship.