In this uneven melodrama from writer-director Derek Cianfrance (Blue Valentine), an Australian lighthouse keeper (Michael Fassbender) and his wife (Alicia Vikander), reeling from their second miscarriage, discover a rowboat that has washed up on shore carrying a dead man and a crying baby girl. Based on a 2012 novel, the narrative is gripping in its first half: the husband, a quiet World War I veteran, delights in their unofficially adopted daughter but wrestles with guilt feelings as her wealthy birth mother (Rachel Weisz), who lives on the mainland, publicly grieves for the vanished child. The lead actors all weep convincingly, yet Fassbender and Vikander seem too awkward together to have been living side by side for years. At the climax the wife makes a decision antithetical to her character, and a morally complex film derails into hackneyed Nicholas Sparks territory, complete with a tacked-on epilogue to tie up all the loose ends.