It tells the story about Viktor (Tom Hanks), who's country suffers a coup while he is arriving to the US. For this reason, he has to stay at the airport, as he cannot get into the country. A great variety of situations happen to him while he lives in the airport: from really hilarious to really sad situations.
The movie is great, not only for the plot but for the acting. Hanks shows once again how talented he is, interpreting the lost Viktor in the huge airport. Personally, I think there's nothing to say against this movie: just perfect. I couldn't move from my seat from the start to the end.
So, if you're thinking of buying a comedy based on an original idea, I recommend you go for "The Terminal". Be sure you won't regret yourself.