Experiment in Terror (1962)

When the bank clerk Kelly Sherwood arrives home after hours, she is intimidated by a stranger that knows her routine habit. He threatens Kelly and her sister Toby to force her to heist $100,000 from her bank; otherwise he will kill her. Kelly does not see his face but notes he is asthmatic. Kelly succeeds to lure the criminal and contacts the FBI agent John 'Rip' Ripley that advises Kelly how to behave and assigns a group of agents to keep Kelly and Toby under surveillance. But when Toby is abducted by the stranger, Kelly tries to stay calm to help the FBI to catch the criminal.