Twenty-eight days after a killer virus was accidentally unleashed from a British research facility, a small group of London survivors are caught in a desperate struggle to protect themselves from the infected. Carried by animals and humans, the virus turns those it infects into homicidal maniacs — and it’s absolutely impossible to contain.

A group of American teens comes Ireland to visit an Irish school friend who takes them on a camping trip in search of the local, fabled magic mushrooms. When the hallucinations start taking hold, the panicked friends are attacked by ghostly creatures; never able to determine if they are experiencing gruesome reality or startling delirium.