What is the expostition of Through the Tunnel by Doris Lessing?

In the beginning of the story, we see the concern that each of these characters has for one another. Jerry and his mother are heading to a beach and Jerry sees a bay that looks intriguing. His mother asks him if he would rather go somewhere else and being the good son, he says no. Finally, he admits that he would rather go exploring. His mother grapples with the idea and then decides that though she is worried about him, she will let him go.