Autumn, 1917. London is not the city that Dr John Watson and Sherlock Holmes once bestrode like giants. When Watson's concert-going companion, Sir Gilbert Hardy, is kidnapped there's a gruesome ransom, for Sir Gilbert and four others, which will involve terrible mutilation unless the demands are met. Help comes from an unlikely source: Watson's old ruthless adversary, the 'She Wolf' Miss Pillbody. She makes him a remarkable offer and so an unlikely partnership is formed—the enemy spy and Sherlock Holmes's faithful companion, a detective duo which will eventually uncover a shocking case of state-sponsored murder and find Watson on board a German bomber, with a crew intent on setting London ablaze.