It's 1986 and 29-year-old Marlo O'Sullivan of London-Irish stock has just found out that his sister is his mother. To steady his life, he moves to Glengarriff, to a cottage he has inherited, in the stunning Beara Peninsula. When a neighbour dies unexpectedly, Marlo takes over his minibus service to Cork. There is nothing regular about the regulars on the bus - especially Sully, a non-verbal 6 year old, who goes nowhere but does the journey back and forth every day, on his own. Marlo is landed with this a strange but compassionate arrangement, fashioned to give the child's mother respite from his care. Sully's obsession with an imaginary friend in the ancient oak forests of Glengarriff slowly unveils its terrible secrets – a 400-hundred-year-old tragedy reveals itself.