On his way through town in his new motorcar, Roy causes a commotion and spooks the horse of village dentist Arthur Peters.

Arthur then explains that all the women in his family including Jennifer inherit a strange ability, able to stop any mechanical device they encounter from working.

Later, Jennifer attempts to stop a smash and grab robbery but ends up being bundled into the thief's car, which breaks down.

Jock rescues her from the police and writes an article about her involvement in stopping the robbery which prompts Angela to become interested in her story.

They are too late however and the converted Handley Page Halifax takes off with Jennifer, Jock, Roy, and John Fairfax on board.

She then tries to return to London but is turned away at the train station and by buses and motorists who have read the story, so asks Carole for help.

With Carole's help Jock sneaks up to her room, however Jennifer furiously kicks him out after he suggests accepting the challenge to prove her powers.

Later however Jennifer agrees to the challenge when Arthur suggests Jock might lose his job if people don't believe his stories.

No effort is made to explain how the girl, brought up in luxurious, sophisticated surroundings, could possibly have reached the age of eighteen without becoming aware of her unusual powers.