Rookie Brimob officer Rama joins a 20-man squad led by Sergeant Jaka and Lieutenant Wahyu for a raid on an apartment block with the intent of arresting crime lord Tama Riyadi. Together with his lieutenants Andi and Mad Dog, Tama runs the block and allows criminals and addicts to rent rooms under his protection. Arriving undetected, the team sweeps the first floors and subdues various tenants; they also meet a law-abiding tenant named Gofar delivering medicine to his sick wife. Continuing to the sixth floor, the team is spotted by two young lookouts, one of whom raises the alarm.

Tama calls in reinforcements and the team suffers casualties. Tama cuts the lights and announces over the PA system that the officers are on the sixth-floor stairwell, and that he will grant permanent residence to those who kill them. The remaining team members are ambushed by shooters from above, and are almost completely wiped out. Prior to the gunfight, Wahyu confesses to Jaka that he staged the mission so he can eliminate Tama, who is in league with corrupt police officials, including himself; the mission is not officially sanctioned by police command, and there will be no reinforcements.

The remaining officers—Rama, Bowo, Jaka, Wahyu, Dagu and three others—retreat to an empty apartment and are cornered by more armed thugs. Rama uses an axe to create a hole in the floor so the team can descend to the lower level. Dropping to the room below, the team struggles to fend off Tama's thugs; the three other officers are killed and Bowo is gravely wounded. Rama uses a propane tank to construct an improvised explosive device that eliminates the invading henchmen. With more of Tama's reinforcements approaching, the team splits into two groups: Jaka, Dagu and Wahyu retreat to the fifth floor, while Rama and Bowo ascend.

After fighting a group of assassins, Rama and Bowo locate Gofar's apartment, and Gofar reluctantly hides the officers inside. A gang wielding machetes search the apartment, but fail to find them. After tending to Bowo's wounds, Rama leaves to search for Jaka's group. Rama encounters the machete gang and defeats them in a long fight, tackling their leader through a window and plummeting onto a fire escape below. On the sixth floor, he finds Andi, who has murdered two of Tama's men. Andi is revealed to be his estranged brother, whom Rama signed up for the mission to search for, at the urging of their father. Rama refuses to leave the building without his comrades, and Andi refuses to abandon his criminal life. Rama parts ways with his brother to search for his surviving colleagues.

Mad Dog discovers Jaka and his group on the fourth floor. Wahyu runs off, and Jaka instructs Dagu to protect him. Mad Dog challenges Jaka to hand-to-hand combat; he ultimately gains the upper hand and kills Jaka, by breaking his neck. Mad Dog then meets up with Andi to report back to Tama. Tama, having learned of Andi's treachery through his surveillance cameras, attacks and incapacitates Andi. Rama regroups with Dagu and Wahyu, and they head for Tama on the 15th floor, fighting through a narcotics lab along the way. Rama separates from Dagu and Wahyu when he discovers Mad Dog torturing Andi. Mad Dog lets Rama free Andi, and fights them both. After a long and brutal fight, Mad Dog is ultimately killed by Rama and Andi.

Meanwhile, Wahyu and Dagu confront Tama. Wahyu kills Dagu before taking Tama hostage. Tama taunts Wahyu by revealing that he knew they were going to raid the building, and that Wahyu was set up by his corrupt superiors and will be killed regardless. Wahyu kills Tama and then attempts suicide, only to find he is out of ammunition.

Andi uses his influence to allow Rama to leave with the injured Bowo and a detained Wahyu. Andi also hands over blackmail recordings Tama made of the corrupt officials he dealt with, telling him to contact Officer Bunawar. Rama asks Andi to come home, but Andi refuses, and asserts that he can protect Rama in his role as a gang boss, but that Rama cannot do the same for him. As Andi turns around and walks back to the apartment block, Rama, Bowo and Wahyu leave.