Dublin, Ireland, 1881. Will and Isobel Fitzgerald settle into number 30 Fitzwilliam Square, a home they could once only have dreamed of. A baby is on the way, Will takes over the Merrion Street Upper medical practice from his father and they are financially secure. But when Will is handed a letter from his elder brother, Edward, stationed with the army in India, the revelations it contains only serves to further alienate Will from his father.

Isobel is eager to adapt to married life on Fitzwilliam Square but soon realises her past can never be laid to rest. The night she met Will in a brothel on the eve of his best friend's wedding has devastating and far-reaching consequences which will change the lives of the Fitzgerald family forever.