The film takes place in an alternate present where fantasy creatures exist in the modern world together with humans. Humans live in uneasy peace with orcs and elves after the three races fought for thousands of years. In Los Angeles, veteran police officer Daryl Ward (Will Smith) has been involuntarily partnered with Nick Jakoby (Joel Edgerton), the city’s first orc police officer. Jakoby is ostracized by humans and orcs alike for wanting to become a police officer. In addition to the pushback from other officers, Ward is personally ambivalent towards him following an incident where it seems he might have let a fellow orc who shot Ward escape. During their patrol, Ward forces his partner to watch an orc being beaten during arrest by a group of fellow cops in order to make a point about where Jakoby’s loyalties need to be, before they are called to arrest an unkempt man with a sword. During the trip back to the station, the man tells Jakoby in Orkish that both officers have become involved in a prophecy and that Ward is blessed. When pressed what the conversation was about, Jakoby lies and says the man was talking nonsense. While Jakoby is booking the prisoner, Ward is approached by Internal Affairs who say they also believe Jakoby put his ethnic loyalties before his partner. Ward, faced with significant financial burdens, is then pressured to agree to getting his partner to confess on tape so they will have a politically acceptable excuse to fire Jakoby.
It later turns out during an interrogation conducted by Kandomere (Edgar Ramirez), the elf working in the FBI’s magic division, that the man on the street is part of a fringe militant group named Shield of Light that is preparing against the return of the Dark Lord. The group believe that all the guns in the world will ultimately be useless and it is only through the use of magic that such a victory will be won.
That night, Ward and Jakoby respond to a disturbance at what turns out to be a Shield safehouse; inside are a number of corpses clearly killed in unnatural fashion, including the torso of an elf woman embedded in a wall. They apprehend the lone survivor, a young elf named Tikka (Lucy Fry) in possession of a wand. When backup arrives, the officers — who have all previous expressed hatred for Jakoby — declare they are stealing the wand for themselves and it’s up to Ward whether one or two officers will die ‘heroically’ to cover up the theft. Although Ward agrees under duress to murder Jakoby, when he leaves to carry it out, they decide to kill Ward anyway. Outside, Ward pulls his gun on Jakoby to force him to confess to letting the orc escape, and is surprised when Jakoby admits to letting the suspect escape but only because he mistakenly cornered the wrong person and realised the imminently arriving backup would most likely execute any orc suspect even if they weren’t the shooter. Faced with the moment of truth by the arrival of their colleagues, Ward instead manages to gun all four of them down before convincing the shocked Jakoby about the truth of the matter. The incident, however, attracts the attention of a local gang, and the two officers and Tikka flee with the wand while under fire. Inferni member and owner of the wand, Leilah (Noomi Rapace), then arrives at the safehouse to find the wand and the Shield-protected traitor, Tikka, both absent. She slits the throat of the elf embedded in the wall, who was tasked with killing Tikka with the wand. After fatally extracting an eyewitness account of what happened from a nearby family, she and her minions also give chase.
A binding ward on the wand prevents it from travelling a certain distance from its owner, forcing the trio to head back into the sprawl on foot. After the gang members flush them from their initial hiding place, they make the mistake of fleeing through the territory of the Fogteeth Orc clan, causing a violent confrontation between the gang and the clan. Abandoning their uniforms and entering a strip club isn’t enough to escape pursuit, but before the gang’s leader can carry out his threat to lock the doors and burn the building to the ground, the Inferni apppear and slaughter them all, giving the trio the opportunity to escape again. Going to ground in a service station, Ward contacts Sherrif’s Deputy Rodriguez (Jay Hernandez), who as a friend from outside the LAPD he hopes will be unlikely to want to kill them. Rodriguez contacts Kandomere, who tells Ward that he will be safe from prosecution for killing police officers if they can keep the wand out of the wrong hands. As Rodriguez prepares to bring them in, he and the station attendant are killed by Leilah’s minions, forcing the trio to flee again as the exploding station draws Kandomere closer to them.
The three again run into the Fogteeth Orc clan and are dragged before its leader Dorghu (Brad William Henke), who is both enraged at the chaos they as police officers caused in his neutral territory, and aware of the possibility they have a wand. Dorghu orders his son to kill them after failing to find the wand. However, as his son was the one Jakoby allowed to escape, their honor code won’t let him do it so Dorghu regretfully kills Jakoby himself. After a brief struggle, Tikka reveals herself to be a Bright by removing the wand from inside her sleeve and using it to resurrect Jakoby, but injuring herself. As this is in accordance with the prophecy Jakoby had been told about earlier in the day, in awe the clan allow the trio to go free. Realising that the two officers can now be trusted, Tikka speaks to them in English for the first time, explaining about the Inferni plan to resurrect the Dark Lord and that she is a traitor to that order whom the Shield of Light had been protecting.
The only way to save Tikka’s life is to place her in one of the magic pools that are found in Shield safehouses but Leilah has anticipated this. There are enough large calibre weapons lying around to defeat the ambush and kill all three Inferni; Leilah is, however, powerful enough to heal herself. She incapacitates the two officers and attempts to first seduce, then kill Tikka. Ward opts to sacrifice the trio to end Leilah, only to discover that he is a Bright. Tikka shouts an incantation which he repeats to cause the wand to disintegrate Leilah with Tikka disappearing as the building rapidly catches fire. Outside, the Fogteeth and the Feds arrive at the inferno to see Jakoby emerge on his own only to then plunge back inside and emerge carrying Ward: all orcs present unanimously declare him blooded for his acts of bravery.
The next day in an isolation room, Ward awakens to find Jakoby at his bedside and himself restrained as being the more dangerous of the two. When Kandomere appears, Jakoby volunteers the truth before Ward delivers a statement emphatically denying any involvement of magic activity or police corruption, seeing Kandomere wants to contain the incident. The Inferni are publicly labeled as simply an extremist group causing terror and Ward and Jakoby are honored by the city for their actions. At the ceremony, Ward smiles as he spots Tikka walking in the crowd.