A young test subject named Chell awakes from a stasis in the Aperture Science Research Facility by a mysterious voice. Asked to perform certain "tests", Chell makes her way through various rooms and test chambers using the Aperture Science Handheld Portal Device, or the "Portal Gun". The tests challenge her wit and her skill and she is able to overcome various obstacles. In one test, she is asked to use a cube known as the Companion Cube to solve the tests. During the test, Chell grew attached to it but was asked to burn it in the end in order to progress. This proved to be a tough feat for Chell. Later, she learns she is being tested by a demonic robot with evil intentions who killed everyone in the facility using a deadly neurotoxin. After nearly being baked into a cake, Chell manages to escape and she works her way through various office rooms to find her mysterious perpetrator, GLaDOS (Genetic Life and Disk Operating System). After a violent battle in which Chell burns the morality cores put on GLaDOS, the super computer is defeated and Chell goes unconscious due to a violent explosion. Years pass, and Chell wakes up again and is greeted by Wheatley, who is a morality core. He isn't exactly the smartest of all the cores. He goes with her as they plan to escape the facility, which has fallen into complete disrepair. However, during their journey, Wheatley wakes GLaDOS who devises revenge. She makes Chell test once again with the "Portal Gun" and she destroys Wheatley, or so she thought. Wheatley came back to save the day and rescued Chell from the test chambers as they fled out of her reach in the older areas of Aperture. After devising a plan to foil her plans, Wheatley and Chell confront GLaDOS and eventually win by taking her out of control of the facility and putting Wheatley in charge. Little did she know, he was just as corrupt as she was and he sends Chell and GLaDOS in the form of a potato battery into the depths of Aperture down an elevator shaft. Down there, Chell learns about Old Aperture in the 1960's, 70's, and 80's up until Cave Johnson's, the owner, death. GLaDOS also learns as her previous life as Caroline, or Cave's wife. They work their way back up to the top levels and fight Wheatley and ultimately regain control of the facility. Pleased with Chell, GLaDOS decides to let her go free and sends her up to a corn field in the middle of nowhere where she is reunited with the Companion Cube.