4 ideas
In Akunin's fictionalized 1877 campaign, a Russian order to seize the fortress town of Plevna reaches the field saying 'Nikopol' instead. The detour gives Osman Pasha time to fortify Plevna and costs the Russians months of bloody siege. Suspicion lands on Pyotr Yablokov, the cipher clerk and the fiancé Varvara Suvorova came to find, but he was framed by a Turkish agent who exploited a single link in the army's communication chain.
The Turkish agent's endgame is to help the Russians win, not to defeat them. He tempts the glory-hungry General Sobolev to push on and take Constantinople, knowing a Russian advance there would bring Britain and the other European powers into the war against Russia. The sabotage works by feeding the enemy's own ambition until its success produces a coalition against it.
The agent Anwar Effendi hides as Charles Paladin d'Hevrais, a charming French war correspondent. The job gives him legitimate reasons to ask questions, move between headquarters, and befriend everyone, including Varvara. Meanwhile suspicion falls on more obviously foreign or awkward figures, like the Romanian colonel Lukan. When access is the goal, the best cover is a role whose job is to seek access.
Fandorin ignores the camp's social impressions of who seems trustworthy and asks one question of each setback: whose larger plan does it advance? Treating a delay, a murder, or a leak as a move in someone's game points to the one person positioned to profit from all of them. Judging each incident separately, as the gendarme investigators do, points only to whoever was nearest.