Two young girls plot a murder by witchcraft. Soon afterwards a government clerk dies painfully in mysterious circumstances. His colleague James Marwood is asked to investigate – but the task brings unexpected dangers.

Meanwhile, architect Cat Hakesby is working for a merchant who lives on Slaughter Street, where the air smells of blood and a captive Barbary lion prowls the stables. Then a prestigious new commission arrives. Cat must design a Poultry House for the woman that the King loves most in all the world.

Unbeknownst to all, at the heart of this lies a royal secret so explosive that it could not only rip apart England but change the entire face of Europe…