Miles Butler lives an uneventful life with his girlfriend until he discovers the body of his landlord in a neighbouring apartment. The tragedy of this moment makes a deep impression on Miles. His curiosity is aroused when a beautiful stranger moves in, and his fascination with the vacant apartment develops from obsession to psychosis.

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?