Perfect Ending Explained [SPOILER!]

SPOILER ALERT: the following article contains massive spoilers, including the ending. If you have not yet seen the movie, proceed at your own risk, or better, come back to this article later!

SPOILERS AHEAD

Perfect Plot Summary and Synopsis

A brilliant, but troubled robotics engineer is kidnapped by a psychopath who forces her to construct deadly traps for an undisclosed purpose.

Source: Wikipedia (CC BY-SA 3.0).