Newlywed Abby Anderson is unsure whether to call herself a widow. In July of 1860, as the nation teeters on the brink of war, word comes that her merchant captain husband, Clifford, has been lost to the Graveyard of the Atlantic. Rejecting social expectations regarding proper mourning, Abby agrees to assist in an Underground Railroad operation out of her hometown of Woolwich, Maine. But an early October winter storm catches Abby and the fugitive slave family she's smuggling, and they find themselves snowed in with Bill Boudreaux, an Acadian trapper and farmer, and two Abenaki teenagers in the remote Maine wilderness.

The unlikely companions must work together to ensure their survival through the long, harsh winter and find themselves growing closer, creating an unexpected family few societies would approve of-and leaving Abbey with what feels like an impossible choice. When spring comes, she will continue her quest to see the fugitive family safely to Canada. And then, she must decide where she truly belongs.