Year 10,000 HTS. Hyos, a volcanic planet in the Cygnus constellation, is the setting for a thrilling story. An advanced civilization has evolved in the underground Hyos habitat. The whole population is unable to sleep naturally and is dependent on a mysterious sleep machine to provide artificial sleep for people. One day, Leda, a young woman wakes up in the middle of her sleep cycle. Ari, a disabled neurologist, together with his friend Noman, a sleep machine expert, embark on a journey to uncover some disturbing truths, which have implications for the whole civilization on Hyos.