Two sisters guard a monster chained to the pole star. If they ever look away, the world ends.

The sisters are the Zorya, the Slavic goddesses of dawn and dusk. The beast is Simargl, a hound chained beneath the North Star, and the moment they falter, he breaks his chain and devours the sky. That is why they never rest. One throws open the gates of heaven each morning to let the sun ride out; the other closes them at dusk. They are the two faces of Venus, the morning star and the evening star, the goddesses who hold the seam between day and night.

Most people who know the Zorya today met them in Neil Gaiman's American Gods. Long before that, they lived in Slavic folk prayers and charms, in a birch-bark scrap from medieval Novgorod, in the star-lore that farmers read off the dawn. But their religion was oral, and centuries of Christianity nearly erased it.

This book gathers what little survives of them and sets it beside the dawn goddesses of the Indo-European past, to restore the star sisters who have stood between the world and its ending since the day it began.