Fisherman Syracuse (Colin Farrell), a recovering alcoholic, lives with his daughter, Annie (Alison Barry), in a small village on the Irish coast. One afternoon, a mystifying and beautiful girl, Ondine (Alicja Bachleda), gets caught in his nets as he wades along the water. Aboard the boat, Ondine brings Syracuse great luck, seemingly drawing the fish towards his nets. However, the fisherman starts to fear that Ondine may not be meant for this life.