A kid walks into your bookstore and... guess what? He's your son. The one you put up for adoption eighteen years ago. The one you never told anyone about. Surprise!

And a huge surprise it is.

It's a huge surprise to his adoptive mother, Monica, who thought she had a close relationship with Matthew, her nearly adult son. Until he secretly arranged a vacation to Cape Cod so he could meet his birth mother... without a word to her.

It's also a surprise to Harlow, the woman who secretly placed him for adoption so many years ago. She has built a quiet life, running a bookstore with her grandfather, and is happily single... though she can't help gravitating toward Grady Byrne, an old friend who has moved back to town, three-year-old daughter in tow, and no wife in the picture.

When Matthew walks into Harlow's store, she faints. Monica panics. And all their assumptions about what being a parent really means explode...

This summer will be full of more surprises as both their families are redefined...and as both women learn that for them, there's no limit to a mother's love.