The film was made in 3-D and is sometimes revived in that format today. There are a few into-the-lap effects of falling rocks and the meteor appearing out of the screen, but Arnold uses the 3-D rather towards the more uncommon effect of perspective depth, trailing telephone wires off into the distance, shooting up into linesmen’s ladders and the like. The 3-D gives more of a visual edge to some scenes - the descent into the crater, the gauzy shots from the alien’s point-of-view. But mostly what carries the film is its literate story and Arnold’s atmosphere. The only real quibbles one has is the conception of the alien, which is surely far too ungainly to be able to fly. And the heavenly choruses that accompany their flight seems to be overdoing it just slightly. Otherwise it is a genuine classic of the era.

It’s a crucial gatefold film in many regards. It was the first screenplay produced by Ray Bradbury - although Bradbury only turned in a treatment and the finished result was rewritten by Harry Essex. There has been some debate over the years whether the finished result was more due to Essex or Bradbury, certainly Bradbury was not entirely happy with the results. The film saw the directorial debut of Jack Arnold. 

Astronomer John Putnam sees a meteor come down in the desert not far from his home. He rushes there, finding a giant geodesic structure and an amoeboid cyclopean creature, just before the creature brings a rockfall down burying the ship. He tries to convince authorities what he saw but nobody believes him. Later Putnam and then two telephone linemen see the alien flying across the highway. 

Putnam later comes across the linemen, one cold and emotionless and the other standing by an apparently dead double of himself. He realizes that the aliens have duplicated them, along with many others in the town. The aliens kidnap Putnam’s girlfriend, telling him she will come to no harm if he does not interfere and they are allowed the 24 hours they need to repair their ship and return home.