In which the city of Irkutsk, a populous hub of Eastern Siberia and the last bastion of Muscovite power in the Far East, prepares resolutely for siege against invading Tartars, with its diverse inhabitants united by a grand defence effort under the command of the determined Grand Duke. Meanwhile, the political exiles, led by the earnest Wassili Fedor, are pardoned and rallied to form a special corps, embodying the patriotic spirit that pervades the beleaguered town as hope rests on imminent reinforcements.