In London, 1896, private enquiry agent Cyrus Barker's world is upturned when his longtime nemesis, Sebastian Nightwine, previously believed dead, turns up with evil on his mind, launching devastating and secretive attacks against not just Barker, but his network of friends and close associates.

In 1896, Dr. Sun Yat-Sen, would be reformer and revolutionary, turns up in London, running away from China's Imperial Qing Secret Service, who has placed a substantial bounty on his head for his political activities. Captured by those agents, he's imprisoned in the Chinese Embassy until he can be smuggled back to China to face execution.

In the meantime, private enquiry agents Cyrus Barker and Thomas Llewelyn receive the unbelievable news that Sebastian Nightwine is both alive and in London. Not just that, it seems he's taking action against Barker and his close associates. At the same time, they've been hired to find this missing Sun Yat-Sen. With elements of the Chinese secret service, elements of the British government, and Nightwine himself all working against them, Barker & Llewelyn are at risk of being cornered by the deadliest set enemies they've yet faced.