Made by the same Planet Films and director Fisher who produced the superior "Island of Terror" the previous year, this sci-fi/horror effort contains a very similar plot line. The main difference is that the creatures threatening the islanders are not man-made products of science gone mad, but invading aliens from outer space. The first half of the picture is a match for Island of Terror, building a suspense around the unknown. It's perhaps a bit too slow, with Christopher Lee doing a lot of walking about and setting up some kind of experiments. He's also some rare genius - I never figured out how he deduced the whole alien invasion theory - no one else was aware of it. Peter Cushing has a smaller role as a local doctor (he also starred in Island of Terror). Many of the early scenes have potential victims hearing a strange whirring noise in the countryside, sometimes as a prelude to death. The death scenes usually consist of an over exposure in the photography, wiping the picture clear with bright light. This is a little less horrible than the death scenes in Island of Terror. Like Island of Terror, much of the picture is during daytime, though there are some effective night scenes (when not mistakenly photographed during day). In the 2nd half, the story deteriorates, and the ending is an abrupt deus ex machina courtesy of nature, unlike the desperate gamble paying off in Island of Terror. One minute everything seems lost, the next minute - it's the end and problem solved. Very abrupt.