After the accidental death of his free-spirited pregnant wife, Penny, reserved architect Henry struggles to find meaning in his life and in the work that once consumed him. As he continues to work on the house he and Penny were building together, Henry is drawn to a mysterious young runaway named Millie whom Penny had asked Henry to help. Though Millie mistrusts Henry at first, the two build a tentative friendship as she reveals her ambition to build a raft to go find her father who was lost at sea. Taking on the father role he was meant to have, Henry neglects his job and other responsibilities to help Millie on her quest. As they work together, he comes to understand that she can help him to heal as much as he can help her. As Millie prepares to leave, Henry is briefly angered when he discovers that Millie possesses the first photograph Penny ever took of the two of them and the news article about her death, but this anger is forgotten when Millie is struck in the head by her sail and nearly drowns. Learning that Millie simply saw Penny's accident, Henry expresses gratitude that someone else was with his wife when she died. In the end, Henry joins Millie as they set sail together across the Atlantic.