Signs was directed by M. Night Shaymalan, who is noted for movies such as The Sixth Sense, Unbreakable, and The Village. In this film, Mel Gibson and Joaquin Phoenix live on a farm and one day notice something strange has occurred. It turns out there are crop circles on their farm, which are intricate, symmetric designs in the corn/hay fields, and they start to see stories on the news about how this may be the marking of aliens. Most of the movie isn't so much plot or action as it is just tension, as the viewer is as clueless as the characters about what created the crop circles. Will aliens appear or not? One of the good things about the movie is that the viewer does not know the answer to that question until the characters do.
Although this movie was a bit slow and boring at times, the tension was thick and unsettling. I began watching this one night while I was home alone and had to turn it off and finish it in the morning because the atmosphere of the film was creepy. Although I think it is a good movie to watch once, I don't find it very rewatchable and so I think it's one that is better rented than bought. If you like M Night Shymalan's other movies, you might enjoy this. But it's not his best.