Lady Susan and Lord James Haythe, twin siblings of the Earl of Cheriton, have always been unpredictable. Intelligent, attractive and easily bored, they find their privileged life in the heart of the beau mode unfulfilling. For three years they have supplemented their unsatisfactory daily round of balls, plays and conventional entertainments with mischief, trickery and decidedly unconventional activities.
When they announce in the summer of 1820 that they wish to undertake a journey of exploration by coach around the northern counties of England, their family waves them off with relief. Surely such a trip will satisfy the twins' need for novelty, and offer no opportunity for disorder.
The novelty of concealing their aristocratic heritage with plain clothes and simple living soon wears off. But Susan and James discover by chance a failing theatre near Sheffield, and set about 'saving' it.
What begins as a lark soon becomes very serious as Susan and James recognize they are playing with people's lives and futures. They offer hard work and good ideas but also trickery, and they realize the partners in the theatre, care-worn Badgworthy and the enigmatic Redwick deserve better. Redwick, who harbours his own secrets, finds Susan irresistible. And he is determined to discover the twins' identity.
The twins' futures are threatened by the difficulty of unraveling their lies. If society learns of their performances on the stage, they will be plunged into disgrace. When exposure of their masquerade looms, the possibility of scandal turns their adventure into a discreditable exploit.