The secrets of the Moscow Kremlin of the 15th century are dark and bloody. There is a merciless and cruel struggle for power and the throne, for the expansion of possessions, for the collection of land. Grand Duchess Sophia, née Palaeologus, in violation of all ancient customs, is making attempts to clear the path for her son Vasily to the Moscow throne. Her husband Ivan III is expanding the borders of the principality - Vyatka and Kazan have already been conquered and a new cruel, merciless border war is about to break out in the West for the Russian lands under the rule of the Grand Duchy of Lithuania... Against this background, noble and courageous heroes - nobleman Medvedev and his friends honorably fulfill their duty, falling sometimes, in seemingly hopeless situations...