In the third book in the middle grade series that Newbery Honor-winning author Rita Williams-Garcia raved is "brimming with hilarity and sisterly hijinks," Marigold, Zinnia, and Lily Silver return to Cape Cod for a final, unforgettable summer.

The Silver Sisters are heading to Pruet again to visit Aunt Sunny and all the friends they've made in Cape Cod the past two years. Before they head East, the girls make a promise they hope will keep the sister drama to a minimum: no fighting.

But things get off to a rocky start when Marigold, after making it her mission to befriend Chloe, the famous director Philip Rathbone's niece, discovers that Zinnie has swooped in and become besties with Chloe. Once again, Marigold's little sister has intruded on her life.

With the divide between the girls growing deeper, Marigold, Zinnie, and Lily worry it's impossible for them to go a summer without a big fight. The same silver moon may hang in the night sky each year, but the sisters below it are changing in ways they have yet to understand.

If they grow apart, more than a promise could be at risk. But if they grow together...the sky's the limit.