
Chase and August are escorting an annoying accountant named Cecil Rusk - the star witness for the prosecution in mobster Marius Roma's tax evasion trial - to court when they are ambushed by Roma's brother and his thugs. After their car is destroyed, the trio escape on foot through a hail of gunfire. Alone on the streets of Los Angeles, they decide to head out of town, where they believe they'll be safe. But a mole inside the force is leaking information on the detectives' whereabouts to Roma's mob, and it's up to Captain Jensen and Det. Richardson to figure out who it is.
Detectives August Brooks and Chase McDonald meet when August and several officers are being overwhelmed by criminals in an explosive shootout. Chase arrives in his Porche and immediately neautralizes the situation with a grenade launcher. Moments later, August discovers that Chase is his new partner, and they are immediately assigned the case to track down a bomber - nicknamed the Daybomber - who has set off a series of explosions in his quest to warn people of the advances of technology.
Chase and August are at August's gym, where they are volunteering their time to help keep kids off the street and out of gangs. In the boxing ring is Andre, a young fighter determined to stay away from gang violence. But when word comes in that Andre's brother has been shot and killed by a rival gang, Andre swears to avenge his brother's death. Chase and August try to persuade him to let the police handle it, but Andre slips from their grasp in pursuit of the killer. The incident also brings back memories for Chase, who is struggling with unresolved guilt over his former partner's murder by a gang youth.