When a mysterious experiment conducted by an eccentric genius goes terribly wrong, his home is destroyed. The unstable energies created by the explosion create a portal, that drags a passing bus, and its mismatch of passengers, inside into a harsh and forbidding parallel world.
With no communication and armed only with their wits and determination to find help, the survivors navigate hostile jungle until they are exhausted and their plight is further complicated when they step into an ancient city and are met by a group of visiting strangers.
Plagued by doubts and mistrust over whether this group are friends or enemies, the survivors decide to join them on their quest deeper into the silent city, unaware that they are heading into danger. Their presence awakens a terror from the shadows that had lay dormant for centuries; and it is only interested in one thing: feeding.