It's 1822 and Scotland's capital is a city of both splendour and squalor. Kate Dunbar is worked like a slave all day and preyed upon at night in the gloomy vaults that lurk under the Old Town's South Bridge but never gives up hope of a better life for herself and her beloved young brother Andrew.
When wealthy young medical student Richard Hope walks into her life, Kate knows that his interest in her could lead them both into danger. Yet it's not long before the two of them have fallen head-over-heels in love.
Others are watching the young lovers. Radical booksellers Peggy and Nathaniel Henderson have Kate and Andrew's best interests at heart. Their greedy and grasping uncle doesn't, and he soon soon starts laying his own evil plans.
Kate and Richard's passionate and poignant romance intertwines with the richly-imagined colour and pageantry of King George IV's historic visit to Edinburgh in 1822, and culminates in the heart-stopping drama of the Great Fire of Edinburgh of 1824.
Can their love affair have a happy ending or will fate, the evil that threatens them and the rigid rules of class and society allow them only one sweet moment of happiness?