A silver head, a golden mustache, a thundering cart across the sky, and golden apples that work like weapons of mass destruction: this episode constructs the biography of Perun, supreme Slavic god of sky, thunder, war, law, and oak trees. It starts with the Proto-Indo-European root meaning oak and how linguists trace it into a verb meaning to strike, linking Perun to Thor, the Baltic Perkunas, and the Finnish Ukko. It then covers the first written records from Procopius in the 6th century and Helmold in the 12th.

From there it examines the thunder stones (fulgurites and belemnites) farmers believed were his ammunition, a Montenegrin folk song in which three golden apples kill 600 wedding guests, his cosmic rivalry with Veles over the sun and stolen cattle, the nine-altar shrine near Novgorod, and his political peak as guarantor of treaties  ...