Residents of a coastal town learn, with deadly consequences, the secret shared by the two mysterious women who have sought refuge at a local boarding house, the Byzantium.
Isabelle, a geneticist recovering from a toxic marriage, is raising her only daughter, Zoe, with her contentious ex-husband. Zoe means everything to her mother and so when tragedy strikes the fractured family, Isabelle travels to Russia in seeking the help of a world-renowned fertility physician who Isabelle believes can help bring back her little girl.
Rory MacNeil, a rugged old Scotsman, reluctantly leaves his beloved isolated Hebridean island and travels to San Francisco to seek medical treatment. Moving in with his estranged son, Rory sees his life transformed through a newly found bond with his baby grandson.