Set during the final years of England's Victorian era, Ursula Brangwen is the eldest of several children of wealthy Derbyshire farmer Will Brangwen and his wife Anna. Ursula, since age 3, has a fascination with rainbows and after one rainstorm, she runs off with a suitcase hoping to look for a pot of gold at the end of it. Will tries to ease her fascination by making her peanut butter and jam sandwiches with several spreads of different flavoured jam resembling a rainbow.