At Niagara Falls, one of the attractions is a red and blue striped hot air balloon offering rides over the rushing water. The balloon is a day-job for Toby O'Hara, a young man whose night-work is to continue to perfect his father’s design for a flying machine. On the other side of the Atlantic, Ursula Bridgewater, an independent woman from Liverpool, is ungraciously dumped by her fiance, Henry Springton. Ursula turns to the thrill of travel as an escape, and her sights are soon set on Thomas Cook’s famous new tour of America. She chooses a young orphan, Sally Walker, as her travelling companion, but Sally is never going to be quite as prepared for the land of freedom and opportunity as Ursula - and certainly not ready to accept Toby O'Hara’s invitation to see Niagara from a great height…