In Promethia, a giant city driven by "emotional energy", sadness and pain are the fuel to maintain operation, while false happiness is the poison given by the ruler.
Caleb, a former elite law enforcer, is an alien who can "read" the emotions of others. He is burdened with indelible sins and runs an inconspicuous emotion regulation clinic in the lowest corner of the city, struggling to survive.
However, he is forced to step out of the shadows when a "perfect virus" that erases all negative emotions quietly spreads, turning people into soulless puppets of joy.
Joining forces with a mysterious nun seeking the truth, Caleb plunges into the center of a maelstrom of lies, conspiracy, and forbidden technology. He will fight against the ruling machine of the entire city, face the dictator who attempts to enslave everyone with "good intentions", and finally uncover the truth about the tragedy of his life.
In this confusing game where his soul is at stake, he must make a choice: embrace the painful reality, or sink into a false paradise without any price?
