 Years after the Black Mesa Incident, the mysterious G-Man summons Gordon Freeman from his induced slumber. Placing him on a train, he finds himself in "City 17", one of an unknown number of  urban centers  where humans are kept in pseudo-slavery by a mysterious alien race known as the Benefactors. The city is overseen by Dr. Breen, a former administrator of Black Mesa who, after arranging the surrender of Earth to the Benefactors, was rewarded with a leadership position. Humans are now half-way oppressed by themselves. Prisons, concentration camps and urban centers alike are controlled by the Combine, members of a somewhat voluntary system in which participation is rewarded with better living conditions. Among all of this, a rebellion stirs in the shadows, hoping to one day ignite a revolution to free humanity from its distant constraints . . . And the timely arrival of Gordon, the "One Free Man", may prove to be the one chance the rebels have to gain the upper hand . . .