MacCumhaill is a tale of a vigilante who assumes himself to be the reincarnation of the mythical Fionn MacCumhaill. He is obsessed and convinced that modern day Ireland is completely over run by crime and violence and will do anything he can to stop this trend continuing.

In 1843, despite the fact that Dickens is a successful writer, the failure of his latest book puts his career at a crossroads, until the moment when, struggling with inspiration and confronting reality with his childhood memories, a new character is born in the depths of his troubled mind; an old, lonely, embittered man, so vivid, so human, that a whole world grows around him, a story so inspiring that changed the meaning of Christmas forever.