A London family tries to move to the Scottish countryside in the wake of social chaos prompted by pollution. John (Nigel Davenport), his wife Ann (Jean Wallace) and their marriageable daughter Mary (Lynne Frederick) contend with street thugs, murderers and people fleeing deadly toxic clouds in an animalistic struggle for survival. The family is joined by a violent hippie (Anthony May) and his girlfriend Clara (Wendy Richard) as they try to leave before martial law and complete anarchy ensue.