Still grappling with the heavy burden of having to eliminate his fellow assassins, Mike Fallon, portrayed by Scott Adkins, seeks a fresh start away from the chaos of London by relocating to the scenic island of Malta. There, he finds himself working as a hit-man for hire across nearby countries, while also keeping Wong Siu-ling, a fiercely skilled martial artist and descendant of the legendary Kung-Fu master Wong Fei-Hung, on his payroll. They engage in impromptu sparring sessions to ensure Mike remains sharp in his skills.
One fateful evening, Mike reunites with an old acquaintance, Finicky Fred, played by Perry Benson, who is also a former colleague from the first film renowned for using unconventional weapons. Fred reveals that the notorious gangster Big Ray, Mike’s deranged mentor and father figure, has lost his assassin bar due to the fallout from Mike's vengeful rampage. With his reputation in tatters, Big Ray has seen all his clients vanish after the dismal news spread.
Fred finds himself short on cash, having squandered a significant amount on a woman he met online. Mike, skeptical of Fred’s conviction that his girlfriend Leylo is real and is waiting for him in Malta, shows compassion by inviting Fred to stay at his home and assist with contracts. Fred's inventive gadgets prove invaluable, and together, they establish a covert headquarters for planning jobs and testing Fred’s latest gadgets, including a series of explosive suits that initially seem too impractical to function.
After advising Fred to decline a contract on Dante Zuuzer (played by George Fouracres), the reckless heir of a Cosa Nostra clan, Mike continues to hone his skills. Meanwhile, Siu-Ling vows to help Fred find Leylo. However, their drama intensifies when Mike and Fred are abducted by Mrs. Zuuzer, portrayed by Flaminia Cinque. In a tense meeting, she demands Mike track down the individual who placed the hit on her son Dante, promising to spare Fred's life in return. She reveals that Mike's modus operandi was mimicked in the attempted hit on her son—who, despite his dreams of becoming a pop star, spends his days indulging in cocaine.
With the pressure mounting, Mike encounters Big Ray at his local pub, only to learn that Ray, out for revenge, has also come to Malta for a job—with a bounty now reaching €9 million. Determined to protect Dante and keep Fred safe, Mike faces the challenge head-on.
In a bid to save the situation, Mike rushes to a karaoke bar where Dante is performing, only to find that the spoiled heir refuses to part with his watch. Instead, Dante swallows it, prompting a fierce clash with the deadly Freya Du Preeze (played by Zara Phythian), a highly trained assassin. After defeating her, Mike finds himself at odds with Dante, who demands to return to his mother. This leads to a tense exchange where Mike seeks to broker a deal for Fred’s life.
As the chaos escalates, they encounter Yendi the Vampire (portrayed by Faisal Mohammed), who meets his end at Mike's hands. The stakes continue to rise as Siu-Ling expresses her desire to join Mike's world of assassins. After facing off against Poco The Killer Clown (played by Beau Fowler) and Silas the Strangler (portrayed by Peter Lee Thomas), the trio goes to great lengths to ensure Dante's safety.
Finally, in a highly charged confrontation, Mike challenges Oyumi (played by Andreas Nguyen) to a fight for Dante's life. Just as things look dire, Big Ray intervenes to eliminate Oyumi, steering the confrontation in Mike's favor. Reluctant but ultimately empathetic, Ray recognizes the value of friendship and agrees to help Mike protect both Fred and Dante.
In a shocking twist, their reckless decision to lure Mrs. Zuuzer into a trap using a rigged suit results in a deadly explosion, securing them the €9-million bounty. In the aftermath, Fred's romantic aspirations end in disappointment when he learns his online love is unattainable. In an introspective voiceover, Mike reflects on their tumultuous journey, hinting at a promising future where he, Fred, and Ray can forge a new path as they begin the next chapter of their lives, an adventure he describes as “a f**king Belter.”
