In the brutally cold winter of 1936, as his wife lies dying, Henrik Halvorsen takes their daughter with him on a perilous journey. Captain of the coal-fired Manitou, he is charged with transporting railroad cars across an icy Lake Michigan. Five-year-old Fern revels in the freedom of the ferry, making friends with a stowaway cat and a gentle young deckhand, before the sighting of a ghostly ship presages danger for all aboard. Eight decades later, Fern reflects on the dark secret she has kept since that ill-fated voyage.