"Nightwatch: Demons Are Forever" is a fantasy novel by Sergei Lukyanenko, part of the renowned "Night Watch" series. The series is set in a world where supernatural beings, known as Others, exist among humans. These Others are divided into two opposing factions: the Light Others, who strive to protect humanity and maintain balance, and the Dark Others, who seek to exploit their powers for personal gain. The protagonist, Anton Gorodetsky, is a member of the Night Watch, a secret organization of Light Others tasked with monitoring and policing the actions of the Dark Others to maintain the precarious balance between good and evil.