A gang of tough inner-city kids rob Sam as she is walking home in a scary South London tower block. She flees when the gang is attacked by a small alien creature which falls from the sky. While Sam and the police hunt for the gang, a second wave of creatures falls. The gang grabs weapons, mount bikes, and set out to defend their turf. But this time, the creatures are much bigger. Savage and bestial, nothing will stand in their way. And the bunch of no-hope kids who just attacked Sam are about to become her only hope.