Homeless Sofia Waters arrives at a hospital suffering from exhaustion and severe leg pain. She meets Angela, who works for a charity, and tells her her story of being a once famous children's author who lost everything when her family took advantage of her financially.

Sofia later meets a dying woman named Avril, who gives her the key to her villa and instructions to find a valuable diamond and have it appraised by a certain person.

Sofia sets out to find the diamond appraiser but discovers that he has been murdered. She meets a man named Jamie Jamieson, who was the appraiser's business partner and knows the identity of the killer. Together they work to bring the killer to justice and expose a nationwide cartel of diamond dealers who buy diamonds from clients at undervalued prices and sell them on the international market at much higher prices.

With Jamie's help and connections, the diamond is exhibited in galleries and museums, and the Cradle of the White Lioness, Avril's estate, becomes a place for street children and the homeless. Sofia takes over running the Cradle of the White Lioness and shares her experience with the homeless, young, and old.