Three Days of the Condor (1975)
One minute you're a mild mannered CIA bookworm popping out for lunch. The next minute you return to find all of your colleagues dead, with you next on the list. Thankfully not a typical day at work is it? Unfortunately, that's the situation that Joe Turner (code name Condor) finds himself in, as he strives to uncover the mystery without meeting the same ugly demise.