Longhead Bay guest house proprietor Amos (Daniel Roebuck) goes into the woods one evening to investigate the source of an odd noise. It turns out that a meteorite has hit the earth, carrying with it the strangest of passengers - one of the last members of an alien race who, after their planet was laid waste by nuclear war, have evolved into ambulant, talking foreheads. Needing host bodies in order to survive and reproduce, the foreheads have come to Earth to breed. The alien forehead attaches itself to Amos' bonce and rides him on into town to spread to the other humans.

Meanwhile, at the 'Institute for Brain Studying', Dr. Sheila Bexter (Fay Masterson) is undertaking ground-breaking research into where our thoughts really come from. Eschewing the accepted theory of brain-centric thinkulating, she claims to have found evidence that the forehead is the source of human intellect, and has even isolated a chemical compound, 'Foreheadazine', that she believes is linked to intelligence. Scoffed at by the rest of the institute's faculty, she seduces her fellow academic Dr. Philip Latham (Andrew Parks) and persuades him to become her guinea pig. Extracting foreheadazine from donor foreheads she injects it into Dr. Latham in an attempt to increase his intellect. (You may well ask where exactly Dr. Bexter could come by such a thing as 'donor foreheads'. This is handled by the simple expedient of buying some 'from a bloke down the pub'.)

As Dr. Latham's intellect increases, so does the size of his forehead, and the alien-possessed take him for one of their own and reveal their plans to him. Not wishing to see the human race turned into zombies, he turns his supposedly formidable brain to fighting them. As the number of inhabitants of the town possessed by the parasitic foreheads increases, their presence is finally noted by town librarian Millie (Alison Martin) and two sailors on shore leave - Big Dan Frater (Brian Howe) and Dutch 'The Swede' Annacrombie (Dan Conroy). After a spot of research in the local library's 'forehead' section (don't worry, it's meant to be that silly) the trio confront the 'bubbleheads' in a final showdown.

Of course, spending so long telling you the plot might suggest that their is something of substance here but I'm afraid this isn't the case. A parody of 1950s B-movies, most notably The Blob, director Larry Blamire certainly has the look down pat. Longhead Bay is dressed in suitably garish and over-cooked colours, and the actors' make-up applied with an industrial-size trowel. The stop-motion effects of the sentient foreheads are also right on the mark (this film even comes 'Presented By' animation legend Ray Harryhausen, whose own films are amongst those parodied), and the film starts off promisingly enough.

The awful and often ludicrous dialogue of the film's inspirations is sharply observed,and the stilted, almost painfully bad delivery by the actors well-judged. What the film, like the forehead creatures within it, lacks, though, is legs. While there are some genuinely funny moments, after about thirty minutes the film runs out of ideas, and the final hour is pretty much the same material over again. It doesn't take long for the film to become tedious and wearing, which is disappointing, rather than irritating, given how well it begins.

I don't wish to be too harsh on Blamire or his cast, though, as there's certainly something of merit in there, just not enough. I can't help but feel that if this had been a 30 minute piece, perhaps even made for TV rather than cinema, then it would have been considerably more successful. What is probably the biggest problem, however, is that the films that Trail of the Screaming foreheads sends-up are, today at least, parodies of themselves. Not least of these is the most infamous of the genre, Ed Wood's Plan 9 From Outer Space. This is widely regarded as one of the worst films of all time, and is far funnier, albeit unintentionally, than any number of spoofs.

I have studied the chemical composition of this film and find it to contain 2 out of a possible 5 units of filmy goodness.