Autumn 1237... One morning, our contemporary will wake up in the body of the young warrior Yegor from the foreign Yelets. History student, amateur reenactor - can he change the course of history and prevent tragedy in the remaining few weeks before the invasion? Or will he become one of the grains of sand that the Mongol horde will sweep away on its way?! Third book of the cycle. Tumen Buri, Burundaya and Kadana are defeated and scattered, Pronsk and Izheslavets survived several assaults and survived - thanks to the dedication of the Russians and the ingenuity of Yegor! But four tumens of Batu Khan have already besieged Ryazan, and Chinese engineers are already building manzhanik trebuchets and vortex catapults for a decisive assault on the city... And three tumens of the best Mongolian commander Subedei are hurrying to Pereyaslavl-Ryazansky on the Oka ice! They are in a hurry to meet the rati of the great Vladimir principality, following from Kolomna to help Ryazan residents...