A resistance fighter. A part-time employee. A squad of Combine Soldiers. A chase gone wrong.
Explore a post-GLaDOS Enrichment Centre, from the surface to it's murky depths. As Arin Spencer, together with Second Technician Jenn Wells, uncover a cavalcade of new environments, puzzle elements, tests and hazards, all while preventing the Combine from phoning home about what they've found down there. Remember, a lot of people are counting on you.