How Long Is “Arlington Road”?

Widowed when his FBI agent wife is killed in an FBI anti-terrorist operation gone wrong, a college professor becomes increasingly obsessed with the culture and sub-society of these dangerous groups. The arrival of new neighbours gives him new spirit, as they are gregarious and friendly, with two children that his son can be friends with. He is even beginning to see another woman. However, he begins to suspect something is odd about the neighbours, something about the way they don't want him to see certain parts of the house or a set of blueprints they have there. Are his neighbours terrorists... or is the stress of losing his wife merely driving him past the point of paranoia?, A history professor befriends his seemingly bland new neighbors, but gradually comes to suspect that they may be planning an act of terrorism.