Wealthy businessman and single parent Sir Michael Carr (Michael Redgrave) does not know how to deal with his daughter Tansy (Juliet Mills), at that awkward age between teenager and adult. His close friend and employee ex-General Henry Barclay (Roger Livesey) has the same kind of problem with his son. Thomas Barclay (Michael Craig) left the military and has now tendered his resignation from Carr's automobile company.
        Tansy chances to meet American Cornelius Allingham (James Westmoreland) at her father's office. The two teens soon become inseparable friends; she shows him around London, with her father blithely unaware of the relationship. When Carr has to go on a business trip to New York, he sends Tansy along with General Barclay on his fishing vacation in Scotland. She secretly arranges for Cornelius to meet her there. The two see the sights on his motor scooter and eventually go camping together (he sleeps outside the tent), without informing anyone. When Carr realises his daughter is missing, he finds some photographs of Cornelius, assumes the worst, and gets the police to initiate a nation-wide manhunt.