The novel opens with a young Russian woman of "progressive" sympathies, Varvara Suvorova, traveling to meet her fiancé Pyotr Yablokov, who has volunteered to fight in the war between Russia and the Ottoman Empire. Her guide steals all her luggage and disappears as she approaches the war zone, but she is rescued by Erast Fandorin, who has been fighting as a volunteer to forget his tragedy. He accompanies her to Russian army headquarters to which he's bringing an important message. Upon arrival, Varvara is reunited with Pyotr, and Fandorin delivers his message: the Turkish army is advancing towards the Bulgarian town of Plevna, which sits on the road to Sofia and must be taken so the Russian army can easily advance through Bulgaria and into Turkey.Varvara sees little of her fiancé, who is busy with his duties as an army cryptographer, so she spends her time at the correspondents' club, where she meets various interesting characters: Irish reporter Seamus McLaughlin, French reporter Charles Paladin, Romanian liaison Colonel Lukan (unlike Bromfield's English translation, some others use proper Romanian spelling "Lucan"), Russian hussar officer Count Zurov (Fandorin's old friend from The Winter Queen), and the charismatic General Sobolev (based on the real-life Mikhail Skobelev). Fandorin is informed that a Turkish agent, Anwar Effendi, is conducting an intelligence operation against the Russian army and might even have penetrated Russian headquarters. This is confirmed when the telegram directing the Russian army to take Plevna is mysteriously changed to an order to take Nikopol, a strategically irrelevant town. Varvara's fiancé Pyotr, who encoded the telegram, is jailed on suspicion of treason. Fandorin is charged with finding Anwar and uncovering the Turkish plot.
