Attractive lady engineer Eileen Talbot is assigned to help Steve Douglas on a rush project in his office, and she applies her many talents to assure romantic, as well as technical success. Only level headed Katie recognizes her as a manipulating female long before the gullible male Douglases do.

One stormy night while Steve is in San Francisco, Katie is alone in the Douglas house while the rest of the family is attending a ballgame. Her tenseness builds as late in the night she hears a scary rythmic noise, and hysterically calls Steve to report that the family has not yet returned and that she hears a loud thumping sound.