Nearly twenty-five years ago, Kathleen Halloran's brother drowned during the last summer they ever spent with their grandmother on a remote island off Maine's coast. Like a siren's call she can't resist, Kathleen is pulled back to Little Sister Island. She leaves her job and her girlfriend, packs up her few belongings, and moves into her grandmother's cottage.

Molly Cooper loves life on Little Sister, where the islanders take care of their own. Kathleen Halloran doesn't belong here, and her arrival stirs up unwelcome memories for the islanders—including Molly's brother. Molly is certain Kathleen will pack up at the first big blow. When she doesn't, Molly begins to see maybe there's more to Kathleen than she thought.

Sometimes, before you can move forward, you have to look back.