Papa Reily (Gabriel Byrne) once lived the life of a traveller. However, following the death of his wife seven years earlier, Reily has been making an unhappy go of city life; drinking heavily and living on benefits in the most grim of Dublin's tenement blocks with his two young sons. The arrival of the children's grandfather brightens the situation somewhat. Grandfather is a traveller and disagrees with the confines of city life. He brings a gift for the children. A beautiful white stallion named "Tir na nOg". But a white stallion in the poorest areas of Dublin begins to cause unwanted interest and it's not long before "Tir na nOg" is stolen from the boys. And so begins an adventure that takes the children off across the Irish countryside and onto the outer boundaries of their imagination.