Is This Tomorrow by Caroline Leavitt

Ava Lark, a divorcee (and therefore, outcast in the neighborhood - this is the 1950s), rents a house in the suburbs. Her son, Lewis is best friends with the neighbor siblings, Rose and Jimmy. One day Jimmy goes missing, and Ava is treated suspiciously. Years later, Lewis and Rose reconnect and figure out what really happened.

The word to describe this book is "solid." Solid story, solid characters, and solid writing. A great pick for these last days of summer.