At night, police officers in Chicago are answering a call. One officer, Garretti, goes to investigate and finds a white-haired woman with glowing eyes and a giant cockroach stealing food from a supermarket. He calls for backup, but is interrupted by a black man, who simply says “gun”. The officer falls to the ground. The woman takes some food down the hole in the floor through which they entered and asks why they are hiding. The simple reply is because they have to. While they continue to discuss their “Pact“, the cockroach gets aware of a poster with an american flag and rips it apart, before leaving too.
The other police officers enters, but he only sees his partner, who stands up. His partner enters and Garretti tells them that he saw mutants. When his partner asks him where his gun is, Garretti can’t even remember what a gun is. Phipps decides to call his superiors to tell them that they have Morlocks.
In another part of the city, several police cars are chasing a group of armed robbers. One of them has been shot in the stomach. Another tries to shoot at the police, but is shot instead. His blood gets in the eyes of the driver and the car hits a lorry. The wounded robber survived, but when he walks to the police, he looks strange: his pupils have disappeared and body has become transparent. The police shoots at him. The robber hits the ground and then turns into liquid and flows into the sewers, where he reforms. The police officers, after a short discussion whether they should call in the Sentinels, decide to follow him. In the sewers the robber is found by a group of six mutants (three of them are the ones from the supermarket).
Searching he sewers, the police officers suddenly hear a clicking sound and find themselves under attack by the Litterbug (the cockroach-man), who claws at one of them and tells them to leave. Another police officer is attacked by a man with long black hair who can blend into his surroundings like a chameleon and goes by the name Trader. A third officer faces Electric Eve (the white-haired woman) and Angel Dust, another woman with black hair. Angel Dust hits him with superhuman strength, but when Electric Eve wants to electrify the officer, she suddenly electrocutes herself. Trader is shot in his shoulder by the last officer, but he repaid by Litterbug hitting him in the back. Then the Postman, an afro-american mutant, appears and makes the officers forget everything that happened that night. Shatter, the last mutant, a man with a obsidian skin and a baseball bat, tells the robber that they are mutants who are living in the tunnels. The robber identifies them as Morlocks and from what he read on them in the newspapers, he thinks that the Morlocks are cannibals. The Morlocks leave. Along the way, Trader tells the Postman that he isn’t going to take a bullet for anyone again and he asks why the Postman didn’t erase all the officer’s minds. Postman tells him that it’s difficult and that he made too many mistakes. They get to Angel who tells them what just happened to Eve, but the Postman has seen it before and explains that her electrical powers short out her synapses from time to time and she’ll be fine in a minute. He then orders Litterbug to make an escape hole.
The robber asks him whether he may come with the Morlocks. Trader has his doubts : the robber was wanted by the cops and he has a tattoo with the roman number thirteen on his neck, but he us allowed to come along anyway. Postman tells him that his body has fused into a single giant cell and that he is a mutant. He denies it and wants to run away, but Eve electrocutes him. The Morlocks tell Cell that he can’t go home because of the Sentinels. Angel explains that the many electric lines in the tunnels protect them from the tracking devices the Sentinels employ, but if they go to the surface they will be found soon. Cell asks them why they helped him, but Eve replies that they were simply defending their home.
Postman tells Cell about the history of the Morlocks and that despite what the newspapers are writing about them, they are just trying to survive. He then introduces everyone to Cell. After describing Eve’s power the Postman hesitates and then says she is a runaway. Litterbug turns out to be an ex-soldier who went AWOL when he turned into his mutated form. Trader was obviously a stockbroker before he became a Morlock, and he interrupts the Postman before he can tell the new guy anything else about him. Angel Dust and Shatter, who can crystallize liquids, are younger than the others. The Postman then tells him about the “Pact”. Each of the Morlocks has still one thing left to do on the surface and they are going to help each other with that, no matter what it is. After that they will disappear into the tunnels. Cell agrees to join them.
A group of Sentinels arrive at their base. Dr. Metellus, the apparent leader of the base, asks a service-man why they took so long. The service-man reads the data and discovers that this group of Sentinels had encountered a group of six mutants and killed them. Metellus orders the tapes of the extermination to be transferred to him. He tells the service-man about the Morlock-sightings in Chicago and orders him to sent the Sentinels on a 24-hour cover zone over the city.