The plot: a young antiquarian goes on vacation. On the way he meets a young woman on her way to the farm of his sister. In the field she is attacked by a strange drifter who allegedly had been dead for a week. The reason is a new experimental machine the Ministry of Agriculture, through ultrasound, kills pests and insects. When the couple arrives at the farm, they find a man killed by this spectral zombie. The plot thickens with the police investigation, he suspects that all is matter of Satanic hippies and drug addicts.
Interesting spanish-italian co-production is highly influenced by "The Night of the Living Dead", the mythical George A. Romero's film, in their argument and quite relevant details of the action.
The idea is quite original and daring in their proposals, indebted to the society of his time, early 70s, with a strong denunciation of such environmental and generational conflict that always sides with the more progressive positions. Capturing on images is quite striking and generally well achieved (starting with the characterization of the zombies themselves) although some breaks in the script detract from the good original idea.
Movie does not indicate at any time their tight budget and it looks forward to at all times.