The Caligula Effect: Overdose is an enhanced retelling of a role-playing game set inside a virtual reality world called Mobius. Created to shelter troubled people from the pain of their real lives, Mobius traps its inhabitants in an idyllic high school existence, where they are made to relive the same three years of adolescence over and over without end. The protagonist is one of the few to awaken to the truth: that this comforting paradise is an artificial prison overseen by a god-like vocal program known as Mu. Refusing to remain, they join forces with Aria, the former keeper of Mobius, to found the Go-Home Club, a band of students determined to break free of the simulation and return to reality. Standing against them are the Ostinato Musicians, devoted followers who serve Mu and brand the Go-Home Club as dangerous traitors. What follows is a struggle to escape a beautiful lie and reclaim the harsh truth of the real world.