時は19世紀末、大英帝国最盛期のロンドン──。　この国に根付く階級制度に辟易するモリアーティ伯爵家長子・アルバート。孤児院から引き取ったある兄弟との出会いによって、世界を浄化するための壮大な計画が動き出す。名探偵シャーロック・ホームズの宿敵、モリアーティ教授の語られざる物語の幕が開く──!!

In the late 19th century, Great Britain rules over a quarter of the world. Nobles sit in their fancy homes in comfort and luxury, while the working class slaves away at their jobs. When young Albert James Moriarty’s upper-class family adopts two lower-class orphans, the cruelty the boys experience at his family’s hands cements Albert’s hatred of the nobility he was born into. He asks the older of the two boys—who has a genius mind and a killer instinct—to help him rid the world of evil, starting with Albert’s own family!