Donal is a 14-year old who develops a passion for greyhound racing. He works in a kennel, which is owned by Good Joe. Good Joe promises Donal ownership of Donal's favorite greyhound, The Mighty Celt, if the animal wins three races in a row. Meanwhile, Donal's mother, Kate, must adjust her life when O, a man from her past, returns. The political climate of Ireland serves as the backdrop of this story.

A group of American teens comes to Ireland to visit a friend who takes them on a camping trip in search of the local, fabled magic mushrooms. When the psychedelics start taking hold, the panicked friends are attacked by ghostly creatures; but how can they determine whether what they are experiencing is reality or hallucination?