Lucy (Scarlett Johansson), a young woman who was forced by her evil boyfriend to deliver goods for others, encountered a group of Mr. Zhang (Choi Min-sik), a vicious gang leader. She and three men were sewn into the abdomen by Mr. Zhang with a mysterious drug code-named CPH4, in order to sneak the drug into different countries. While wandering in Taipei, Lucy was beaten by the evil man, causing the drug to rupture and enter the blood. Unexpectedly, something incredible happened. The drug stimulated the potential of Lucy's brain, awakening about 90% of the neurons in the brain one after another. With the rapid evolution of the body, Lucy has mastered more and more so-called superpowers. She clearly understood the powerful power of CPH4, so she tried every means to prevent the other three bags of drugs from falling into the hands of Mr. Zhang and his gang. During this period, she tried to get in touch with Samuel Norman (Morgan Freeman), a senior professor of brain research. Under the witness of the latter, Lucy will usher in a historic moment when her brain is 100% awake...