Ireland, 1924. Seamus Óg MacGrianna (Dominic Cooper) is a lighthouse keeper whose elaborate rituals keep him tethered to the past – tending the garden where he once lived and rowing out into the mist every morning to listen for the call of the fabled Each-Uisce that might finally set him free. By night, he guides ships by the light burning in his lighthouse; by day, he has lost his way. But the walls Seamus has created begin to crack when three lives intersect with his own: Edith (Sarah Gadon), the mysterious American, whose quest for closure ignites a long forgotten spark; Father MacGabhann (Aidan Quinn), the hard-line priest who makes it his mission to start a battle of wills with battle a man who has nothing to lose; and Maire (Sarah Bolger), the housekeeper whose unconditional love can no longer