Although set in Kansas, the bank in the movie was filmed in the town of Hartney, Manitoba and city scenes were filmed in Winnipeg, Manitoba. Most notably, scenes of the skating rink were filmed behind the Millennium Library, and the exterior of Chris' apartment was filmed in the Exchange District.
Resulting from his mental incapacitation, he is unable to have meaningful work. Thus he works as a night cleaning man in a small-town bank. It is there he comes under the scrutiny of a gang planning to rob the bank. The leader, Gary (Matthew Goode), befriends him and uses a young woman, Luvlee (Isla Fisher), to seduce him. Confused, but wanting to escape his current existence, he initially goes along with the scheme. After realizing he is being used, he attempts to stop the robbery, which immediately goes awry.
A sheriff's deputy (Sergio Di Zio) stumbles into the robbery while delivering doughnuts to Chris. Guns are fired and the deputy and three gang members are killed. Gary is wounded and one other bank robber, Bone (Greg Dunham), survives. Chris escapes in the car which contains the money they stole; he buries it near where his accident occurred. As this is happening, the robbers kidnap Lewis to get the money back. The robbers and Chris meet to exchange the money for Lewis, but they force him to take them to the site of the buried cash.
While Chris digs in the snow to retrieve the money, Gary's health is rapidly deteriorating. Chris gives one of two bags to Bone, who then prepares to execute Lewis. Chris shoots Bone with a shotgun he'd hidden in one money bag. At the same time, Gary collapses and dies from loss of blood. Chris returns the money and turns himself in. An investigation by the FBI concludes that Chris could not have pulled off the robbery, by himself, due to his mental state — confirmed by video surveillance of the robbery.
The film concludes with Chris and Lewis opening a restaurant financed by the manager of the bank.
The Lookout won the award for Best First Feature at the 2008 Independent Spirit Awards.