I hadn't watched this film before, but Signs appeared on TV with a favourable review so I thought it was worth a look. It certainly has some cinematic firepower, with M. Night Shyamalan writing and directing (plus appearing in a minor role) and Mel Gibson and Joaquin Phoenix heading the cast.
The story starts with the discovery of crop circles on a farm where Graham Hess (Gibson), his young son and daughter, plus younger brother Merrill (Phoenix), live together. There are also suggestions of something nasty lurking in the cornfield, the dog showing alarm and so forth, but nothing is seen. Graham, who we soon learn is a former priest who lost his faith when his wife was killed in a road accident and is now thoroughly sceptical, initially doesn't believe there is anything there. Meanwhile, the TV is showing films of lights in the night sky appearing over major cities.
The pace of the film is slow and deliberate, focusing on the atmosphere of growing menace and the confusion and, ultimately, terror of the family as their worst fears are realised. It is only relieved by a few moments of deadpan humour, particularly concerning tin-foil hats!
I found the second half of the film more disappointing than the first. It had seemed to be shaping up to be a psychological study of the nature of belief, in both religion and conspiracy theories, and the impact of this on an isolated group of people, while keeping the reality or otherwise of the threat uncertain. Handled differently, with the truth of the situation remaining unclear to the viewer, this could have been a landmark production. Instead, it turns into more of a routine horror film as the nasty aliens come into the open at last and besiege the family. Still worth seeing – once.