The film opens with Indonesian SWAT officer Rama praying, practicing silat and bidding goodbye to his wife, who is pregnant with his child.
Rama joins a 20-man elite police squad, including Officer Bowo, Sergeant Jaka, and Lieutenant Wahyu, for a raid on an apartment block in Jakarta's slums. The team intends to capture crime lord Tama Riyadi, who owns the block and lets criminals around the city rent rooms under his protection. Arriving undetected, the team sweeps the first floors and subdues various criminal tenants; they also temporarily detain an innocent tenant delivering medicine to his sick wife. Continuing undetected to the sixth floor, the team is spotted by a young lookout, who raises the alarm before he is shot and killed by Wahyu.
Tama calls in reinforcements, who ambush the police officers patrolling the outside and the first five floors, killing and maiming a majority of them. Cutting the lights, Tama announces over the PA system that the police are trapped on the sixth floor stairwell, and he will grant free permanent residence to those who kill the intruders. In the darkness, the team is soon ambushed by shooters from above and behind, killing of a great number of them. Jaka learns from Wahyu that the mission is not officially sanctioned by the police command; nobody knows their location, and no backup or reinforcements will arrive. The remaining officers are forced to take cover in an empty apartment, where Officer Bowo is shot and injured by a mob of pursuing tenants. To save him, Rama constructs an improvised explosive device that kills the tenants, giving them a small window of time. With more antagonists approaching, the team splits into two groups covertly: Jaka, Wahyu, and Dagu retreat to the fifth floor, while Rama and Bowo ascend to the seventh.
Fighting their way to the apartment of the innocent tenant they released earlier, Rama and Bowo plead with him to help them; although his sick wife urges him to not get involved, he reluctantly agrees and hides the officers in a secret passage. A machete gang arrives and ransacks the man's apartment, but when they fail to find Rama and Bowo, they leave. After tending to Bowo's wounds, Rama leaves him with the couple to search for Jaka's team; however, he crosses paths again with machete gang. He manages to dispatch one member and flee, but is forced to fight the rest of them with his bare hands. Rama defeats and kills most of the gang, including their leader, who he uses to soften his fall when he jumps out of a window to an apartment below to flee another mob of pursuing tenants. He then continues his search, only to be captured by Andi, Tama's right-hand man. It is then revealed that Rama and Andi are estranged brothers, and that Rama signed up for the mission to search for Andi and convince him to return home, at the urging of their father.
Concurrently, Jaka and his group are found by Mad Dog, Tama's ruthless henchman. Wahyu flees, and Jaka orders Dagu to follow Wahyu. Mad Dog captures Jaka, but instead of shooting him, Mad Dog challenges him to hand-to-hand combat. After Mad Dog defeats and kills Jaka, he drags the corpse to an elevator. Andi tells Rama to wait before leaving and meets up with Mad Dog. However, Tama has seen Andi talk to Rama on the numerous security cameras in the building. Realizing Andi's betrayal when he didn't return with a corpse, Tama stabs Andi in the hand and turns him over to Mad Dog.
Rama regroups with Wahyu and Dagu, who go on to fight through a narcotics lab, and they head for Tama on the 15th floor. Rama, finding Andi being beaten by Mad Dog, separates from Wahyu and Dagu to save him. Mad Dog allows him to free Andi and fights both brothers simultaneously. Mad Dog initially has the upper hand, but the brothers prove to be match for him when working together. After an intense and grueling fight, Mad Dog eventually overcomes the brothers, but is stabbed in the neck by Andi while trying to finish off Rama. This weakens him enough for the brothers to finally kill him.
Meanwhile, Wahyu and Dagu confront Tama, only for Wahyu to betray and kill Dagu. Wahyu takes Tama hostage with the intention of using him to escape, but Tama taunts Wahyu by revealing that Tama has been waiting for the team before the events of the movie began and Wahyu was set up by his corrupt higher-ups; even if Wahyu escapes, he will be killed later. Wahyu kills Tama and attempts suicide, only to find that he has no bullets left.
Andi uses his influence over the tenants to allow Rama to leave with Bowo and a detained Wahyu. The tenant who protected Bowo watches from a window and grins with delight. Andi also hands over numerous blackmail recordings Tama made of corrupt officers taking bribes, hoping that Rama can use them to his benefit. Rama asks Andi to come home, but Andi refuses, due to his acclimation to his criminal lifestyle. Before Rama leaves, Andi asserts he can protect Rama in his role as a criminal boss, but that Rama could not do the same for him.
Andi turns around and walks back to the apartment block with a grin that breaks into a wide-smile, whilst Rama, with Wahyu and an injured Bowo, exits to an uncertain future.