The picture features the life and deeds of Boris I - strong historic personality, which completes his mission to the full and at the end of his life receives holy orders. Prince Boris I is ruling in the late 9th century. In his youth, he, the brilliant statesman and diplomat, is experiencing heavy defeats in the wars he wages against his neighbors. Nonetheless, he manages not to cede any territories to the enemies. Under his rule, Bulgaria breaks with paganism and joins the Christian community, paying an exorbitant price, a heavy death toll, but there is no other way. The adoption of Christianity in 864 was a historical event of great significance. It guaranteed Boris I much need peace with the Eastern Roman Empire and allowed him to merge the numerous tribes inhabiting the country into a unified nationality and later to found a state. Boris I introduced the Slav script, thus turning Bulgaria into the cradle of Slav culture.