When Lucy's (Scarlett Johanson) boyfriend tricks her into delivering a suitcase to Mr Jang, a Korean gangster, she ends up becoming an unsuspecting drug mule. She's had a package of CPH4 inserted into her abdomen and is tasked with delivering the package to Europe along 3 others. When Lucy is beaten and kicked by one of the gang members, the package splits and the drugs begin to leak inside her body.
The main storyline focuses around the nootropic substance known as CPH4 which begins to expand Lucy's brain power. As the drug works its way into her cells, she begins to experience new things such as telekinesis abilities, an expanded consciousness.