In return for her kindness, scholar Li Bai Chang presents young cook Kat with a rare and precious box of tea. Kat thinks no more of her unusual visitor until two days later when the kitchen erupts with the news that Lady Cynthia's neighbour has been murdered. Known about London as an expert in the language and customs of China, he acted as intermediary for merchants and government officials. But Sir Jacob's dealings were not what they seemed, and when the authorities accuse Mr. Li of the crime, Kat and Daniel find themselves embroiled in a world of deadly secrets, from Mayfair to Kew Gardens.