Deus Ex takes place in the year 2052 in a dystopian cyberpunk future on the brink of social and economic collapse, where multiple conspiracy theories and organizations are real.[9][10] The two main factions in-game are the Illuminati, portrayed as an ancient secret society controlling civilization from the shadows, and Majestic 12, once subordinate to the Illuminati and now a splinter group. During the events of Deus Ex, the world is being ravaged by a plague dubbed the Gray Death, with supplies of its Ambrosia vaccine limited.[9] The game takes place across multiple locations including multiple parts of the United States (New York City, California, Nevada), Hong Kong, and Paris. A recurring location is Liberty Island, which houses an operating base for the United Nations Anti-Terrorist Coalition (UNATCO). UNATCO's main conflict is with the National Secessionist Force (NSF), a terrorist group targeting Ambrosia shipments.[9][11] Another feature of the world is "augmentations", artificial enhancements using mechanics and nanotechnology.[9]
The main protagonist is JC Denton, an agent for UNATCO who has received advanced nanotechnology; he works at UNATCO with his brother Paul Denton, who shares the same nanotech augmentations, under the command of Joseph Manderley. Other important characters are Tracer Tong, a hacker allied with the Triads of Hong Kong; Morgan Everett, a high-ranking Illuminati member; Daedalus, an artificial intelligence construct and its successor Icarus; Walton Simons, newly appointed Administrator of the Federal Emergency Management Agency (FEMA); and Bob Page, a corporate CEO and current leader of Majestic 12.[12][13]