Paul Hoplin (Rod Steiger) is the mastermind of a crime to collect a $500,000 ransom, threatening to use an explosive device that Jim Molner (James Mason) designed. He and his gang are holding Molner, wife Joan (Inger Stevens) and young daughter Patty (Terry Ann Ross) hostage.
The tranquility of a small town is marred only by sheriff Tod Shaw's unsuccessful courtship of widow Ellen Benson, a pacifist who can't abide guns and those who use them. But violence descends on Ellen's household willy-nilly when the U.S. President passes through town... and slightly psycho hired assassin John Baron finds the Benson home ideal for an ambush.
After being released from prison on a bum charge, Harry Barber is out for payback to regain his lost two years. He's hired by Mrs. Malroux to fake the kidnapping of her stepdaughter (the daughter of a dying millionaire). He discovers that he is being set up on multiple levels and will soon face a longer sentence if he doesn't prove the truth.
A savings-and-loan bank is robbed; later, a police wiretap identifies meek bank teller Leon Poole as the inside man. In capturing him, detective Sam Wagner accidentally kills Poole's young wife, and at his trial Poole swears vengeance against Wagner. Poole begins his plans to get revenge when he escapes his captors.