At Niagara Falls, Toby O'Hara offers rides over the rushing water in a red and blue striped hot air balloon. The balloon is a day job for Toby, his 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 fiancé. Ursula turns to the thrill of travel as an escape, and 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.
Together these indomitable characters are lifted by small acts of bravery to find - surprised and heartened - that what once seemed terrifying is in fact the opposite...