After losing her mom in an accident, a teen and her father welcome a distant cousin named Sienna into their household. Hoping to claim the family as her own, the psychopathic Sienna hatches a devious plan to recreate the prom she never experienced.

When a possessed pair of jeans begins to kill the staff of a trendy clothing store, it is up to Libby, an idealistic young salesclerk, to stop its bloody rampage.