The Golden Horde S01 E15 Episode 15

During the visit of the Yaroslav Embassy to the Horde, Ustinya learns that Khan Berke was given a letter, in which Boris tells the truth about Mengu-Temir and his embassy to Russia. She persuades her lover to flee to Hulagu; the army stands at the borders. Berke's days are numbered, and Mengu, will become Hulagu's faithful ally. Yaroslav becomes ill, unknowingly due to a slow acting poison.