Every night, seven-year-old Lily fights a losing battle against the shadows in her room, terrified of the dark. But on the coldest night of winter, a ghostly, beautiful steam train made of frosted glass and starlight pulls up directly outside her bedroom window. Boarding the Slumberline Express, she meets Conductor Silas, a gentle caribou with galaxies in his antlers. Together, they embark on a journey to the Aurora Station at the top of the world, teaching Lily that the dark is not a place for monsters, but a quiet, velvety canvas waiting to be painted with the beautiful light of her own dreams.