An alien drops into the middle of a South London mugging (5 public housing thugs are dispossessing a young woman of her belongings). The alien is a cross between a wolf and Gollum. The boys chase it down and kill it. Apparently, it was well-thought of, because shortly thereafter, a whole bunch of these things come from space for revenge. Good, scary fun, a few good lines, and tense action sequences, not terribly marred by some unnecessary suggestions of the poor plight of London’s youth, forced to mug and terrorize by the inequities of an uncaring society.