A segregated town, a hidden boy, a courageous girl - and a mystery in desperate need of solving.

San Francisco, 1900. Thirteen-year-old Lizzy Kennedy is not like the other girls in her town. She'd much rather be helping her doctor father with his patients than be stuck in frilly dresses and learn how to dance - but unfortunately for her, society (and her Aunt Hortense) has other ideas about what is 'proper' for a young lady. This includes not poking your nose in other's people's business - but then Jing, their beloved housekeeper, gets stuck in the Chinatown quarantine. Fear rules San Francisco - fear of the Chinese, and mostly fear of the plague rumours that circle them. Lizzie knows she has to help Jing, whatever the warnings. But what she doesn't expect to find is a strange boy hiding in Jing's room.

The boy is called Noah. He says he's Jing's son - although Lizzie's never heard of him - and although he's escaped the quarantine, he can't risk leaving the house in case he gets rounded-up too. Lizzie wants to investigate, but it seems her questions only get people riled up. Is there really plague in San Francisco? What have the Chinese got to do with it? Just what or who is the mysterious 'monkey' - and what has his secret got to do with anything? Lizzie will have to use all of her courage, instinct and cleverness to unravel the mystery of the monkey's secret, save Jing, Noah and Chinatown - and maybe even her change her own destiny.