Tim and Milli have lived together for several years and no longer understand whether their relationship is built on love or has already become a habit. They move to a small town outside a large city, where she begins working as a teacher, and he is still trying to record a music album. One day the couple goes for a walk in the forest, falls into a mysterious cave, and spends the night there. The next day Tim notices that something strange is happening to him: it is physically hard for him to bear Milli's absence, and he is drawn to her by a frightening force.