The movie is about people who survived the atomic war. Almost all the action takes place in the Moscow metro (the world's largest nuclear shelter, which can serve as an underground city), whose stations and passageways are inhabited by people. Thanks to efficient civil defense, the metro network was protected from radioactive contamination - almost all the stations have sealed gates and activated radiation and water purification filters. All indications are that at the time of Moscow's annihilation about 70,000 people could have taken refuge in the metro. Twenty years after the atomic war, the metro is inhabited by 50,000 people. Only half the stations are populated - some have been abandoned, many have been consumed by fires or cut off by tunnel collapses. The movie is based on the novel series by Dmitry Glukhovsky.
