The fate of empires lies with a piece of parchment..
It is the year 1899.
Captain Wentworth in mourning for his wife is lifted from his stupor by two letters received; one from the admiralty and one from an old school friend and midshipman, Hugh Abercrombie. In Abercrombie's letter is an invitation to dinner to discuss a mysterious parchment attached to the letter containing a cipher in Chinese.
At the admiralty, Wentworth is asked by his superiors to act as a liaison between themselves and the innovative, wealthy inventor, Frederick Devereux. Devereux is using his wealth and machinery to assist a Navy operation, attempting to refloat a sunken auxiliary ship off the coat of Kent.
Wentworth travels to Kent where he and Devereux discover it's not a colliery vessel but a state -of-the-art submarine being trialed for the Japanese navy. The Sub has been saboatged and both Wentworth & Devereux believe this to be the case as the cipher's scrip is treated with phosphorous.
Wentworth & Devereux are drawn into a murder, an international crisis and the threat to the Empires of Europe from an anarchist known as Deschamps.