Siiri Tuokkola takes up arms for the Women's Guard during Finland's 1918 Civil War along with her comrades. Stationed in a remote village outpost, rumours of strange things in the woods come to a head when Siiri's comrade Mirva goes missing in a blizzard. Determined to find her, Siiri braves the deep forest, where mysterious lights weave through the trees, and those who look upon them for too long may find themselves afflicted by a strange madness. But there are worse things in the forest than lights, and Siiri must face them if she is to find Mirva before it's too late.