Miami detectives Mike Lowrey and Marcus Burnett are back on the beat, but times have changed. Marcus is now a grandfather and is considering retirement, longing for a peaceful life away from the dangers of police work. On the other hand, Mike remains the same adrenaline junkie, dedicated to his career and unwilling to slow down. Their friendship is tested by these diverging paths, yet they are drawn together one more time when an enigmatic assassin's bullets tie Mike to a troubled past. As Marcus grapples with the idea of settling down, Mike is consumed by a thirst for vengeance and a need to confront an old enemy.

The duo teams up with AMMO, an elite tactical squad in the Miami Police Department, composed of younger, tech-savvy officers. This new team's innovative methods clash with Mike and Marcus's old-school ways, leading to both comedic and tense moments. Together, they must navigate the modern landscape of crime-fighting and track down the assassin before more lives are lost. The partnership between veterans and the new generation highlights a theme of legacy and change, as the two protagonists face both personal and professional dilemmas amidst their action-packed investigation.