The Richenbach Hero faces a new challenge. James Moriarty's apparent return has sent England into a frenzy, and the MI6 is facing flak after losing six agents in order to stop him. An exciting chase through different countries unfolds as one agent goes rogue. Mary is haunted by ghosts of her past, and is abducted by one of them. Will Sherlock track down the agent, save Mary and not play into Moriarty's hands? Will he succeed? or will this truly be a task impossible?