A low-budget film directed efficiently by British horror master Terence Fisher. The cheesy special effects and the poor aliens design don't ruin in any moment this very attractive science-fiction movie. Although the first part of the film is higher up of its last thirty minutes, the movie keeps the interest until the ending. Atmospherical shots, a conventional plot line ( a group of survivors of an environment disaster fight for their lives against an alien invasion )supported by a convincing script and fine actors direction. Not so fine as other science-fiction titles by Fisher himself as " The night of the big heat " or "Island of terror "it contains some splendid, very creative moments like the astoundin gopening credits where we assist to a chain of strange and apparently disconnected accidents ( including a train derailment ): a lesson of cinematographic economy and atmospheric invention worthy of this subversive and very talented director .