The Sentinel
The Sentinel is a crackling good thriller because everyone involved is working at the top of their game. Pete Garrison (Douglas) is on the presidential protection detail when another agent is murdered. A creepy informer tells Garrison about an elaborate assassination conspiracy that's related and well underway. Garrison also happens to be having an affair with the First Lady (Kim Basinger), the stress of which causes him to flunk a lie detector test when word of the plot to kill the president becomes more than just paranoia.