Lucy has evolved into a powerful, omnipresent digital entity. The plot centers on Lucy's return to Earth as a force of nature, tasked with stopping a rogue scientist, Dr. Elias Kane, and his creation, Project Apex, from destroying humanity with CPH4 compound. She partners with a neuroscientist, Dr. Mia Clarke, to combat the threat, leading to a reality-bending confrontation that pushes the boundaries of time and space.