Joe Cornish writes and directs this British sci-fi comedy action adventure starring Jodie Whittaker, Luke Treadaway and Nick Frost. While being robbed by a gang of thugs outside the South London tower block where she lives, trainee nurse Sam (Whittaker)'s hooded attackers suddenly break off their assault when a meteorite hits a nearby carpark. As Sam flees the scene, the gang members fend off an attack from a small alien being that has emerged from the crash-site, killing it in the process, and carrying off their prize to their rooftop lair.

But now, as Sam and the police search for the gang, a new wave of meteorites fall. With the gang emboldened by their latest victory, they prepare to face their new-found enemy, only to be confronted with an army of much larger, savagely vicious alien monsters, hellbent on finding their comrade.