Kelly Sherwood (Lee Remick) is a bank teller who is terrorized by murderer Red Lynch (Ross Martin). Red, whose asthmatic voice is heard through his many terrifying phone calls, threatens to kill Kelly if she doesn't steal a large sum of money from the bank. In an attempt to ensure her compliance, Red begins to threaten those closest to Kelly. Despite her terror, Kelly involves the F.B.I., including Agent Ripley (Glenn Ford), who works to capture Red before the villain can get to Kelly.