Brick Davis is a street-wise New York City lawyer who decides to join the US Department of Justice and become a G-Man after his friend Eddie Buchanan, also a G-Man, is gunned down by mobsters. Davis' schooling was actually paid by a friend, Mac McKay, a benevolent mobster who wanted to make sure that Brick didn't end up on the wrong side of the law. He hasn't been very successful as a lawyer so law enforcement seems to be the next best thing. When mobsters go on a spree of bank robberies in the US mid-west, Davis is assigned to the Chicago field office. As they arrest the mobsters one by one, Davis learns that the rest of the gang is hiding out at a hotel run by his onetime friend and mentor McKay. Things come to a head when the last remaining gunman kidnaps a fellow G-Man's sister.