This article describes the Half-Life 2 storyline, chapter by chapter. The original Half-Life takes place at the Black Mesa Research Facility in 200-. During an experiment, researchers at Black Mesa accidentally cause a Resonance Cascade which rips open a portal to Xen, the only known borderworld. Creatures from Xen flood into Black Mesa via the portal and start killing everyone in sight. The player takes on the role of Dr. Gordon Freeman, one of the research scientists who has been involved in the accident, and who now must escape the facility.