She is forced to smuggle a bag of experimental drugs in her stomach from Asia to Europe.
When the bag splits after a kick to the stomach, Lucy's entire body is overcome by the incredible power of the drugs.
These open pathways in her brain that no human has ever had opened.
Seeking answers to her nightmarish plight, Lucy contacts brain expert Professor Norman (Morgan Freeman).
Norman has maintained the theory that humans use only a small portion of their brains -- 15-20 per cent -- and amazing things could be achieved if any of the remaining, under-utilised grey matter is accessed.
We watch as Lucy hits 30 then 40 then 50 per cent of brain function.
She becomes a formidable foe for Mr Jang (Min-sik Choi) and his henchmen as they try to stop her and retrieve the other bags of drugs from the remaining three "couriers".
What Lucy lacks in firepower she more than makes up for in supernatural powers.
As she nears the magical 100 per cent of brain capacity, Mr Jang's gang closes in.
Professor Norman and the French police need to keep Lucy alive long enough for her to download all the immense knowledge these drugs have allowed her brain to accumulate.
Lucy is gripping and gruesome at the same time.
It gives us some insight into the incredible and deadly powers of artificial drugs and the influence they can have on humans.