The unconventional Lady Jane and her husband Captain Wescott are looking forward to their journey to India. The luggage is already on board, and the ship is set to sail the next morning. However, the famous Orlow diamonds are stolen in London, and a Russian attaché falls victim to a treacherous murder. A first suspect is quickly arrested: it is none other than Wescott's servant Levi, who had regular contact with Russian émigré circles. Reluctantly, Lady Jane and the Captain postpone their trip to exonerate Levi and assist in solving the case. When the Captain suddenly comes under suspicion himself, Lady Jane takes it upon herself, with her own confidence, to free her husband from his difficult situation. The search for the true mastermind behind the murder in London leads her right into the revolutionary circles of St. Petersburg.