Still dealing with his guilt after being forced to kill his assassin co-workers, assassin Mike Fallon (Scott Adkins) moves to the island of Malta to decompress and get away from London, finding work as a hit-man for hire in nearby countries and keeping martial artist Wong Siu-ling (Sarah Chang) (a descendant of Kung-Fu master Wong Fei-Hung who ultimately becomes Mike’s sidekick) on his payroll to fight him at random times and keep his skills sharp.
One night, Mike runs into old friend Finicky Fred (Perry Benson) (Mike’s colleague from the first film who specializes in unorthodox weapon), who informs him that their former boss Big Ray (Ray Stevenson) (Mike’s maniacal father figure and mentor from the first film) lost his assassin’s bar after Mike’s vengeful rampage. Big Ray lost all his clients after word got out that he had lost all his assassins. Fred is out of money due to giving a large sum to a woman he fell in love with online. Mike says that Fred has been scammed, but Fred is sure that his girl Leylo is real and lives in Malta. Fred is in Malta to meet her. Mike takes pity on Fred and allows him to stay in his house and assist him on hits. Fred is really useful in the field with his devices and business is booming. Mike is happy for the first time in a long while. He and Fred put together a secret headquarters to test out Fred’s gadgets and plan jobs. Fred has designed a set of explosive suits, that look just like a normal suit, that Mike thinks won’t work. On Mike’s advice, Fred rejects a contract put out on Dante Zuuzer (George Fouracres), the spoiled heir to a Cosa Nostra organization that even Mike fears. Siu-Ling promises to help Fred find Leylo.
After carrying out another hit, Mike and Fred are abducted and taken to meet with Mrs. Zuuzer (Flaminia Cinque), who asks Mike to hunt down and kill whoever accepted the contract on Dante in exchange for sparing Fred’s life; an attempted hit on Dante had been carried out using Mike’s Modus Operandi. Dante snorts cocaine all day and has dreams of becoming a pop singer, even though his voice is terrible. She knows that the contract on Dante was put out by a corporate CEO out of Scandinavia.
The Zuuzers release Mike, who encounters Big Ray in his local pub – Fred had sent Ray a letter explaining their new business operation against Mike’s advice. Ray vows revenge on Mike, revealing he’s in Malta for a job, and Mike deduces he was behind the attempt on Dante’s life. Ray explains that the client has raised the bounty to Euros 9 million and opened the contract to any takers, as well as hacked into the tracking device in Dante’s watch to broadcast his location. Mike resolves to protect Dante in order to keep Fred alive.
Mike arrives at the karaoke bar where Dante sings, but Dante refuses to destroy his watch and swallows it. Assassin Freya Du Preeze (Zara Phythian) (a highly skilled assassin claimed to have been trained in the dark arts by those who viewed James Bond as a “muppet”) arrives first and kills Dante’s team of bodyguards before Mike fights her and kills her with a barbecue skewer. It is clear that Dante doesn’t like Mike, who keeps pushing him around. Dante orders Mike to take him back to his mother, but Mike talks to Mrs. Zuuzers and agrees to keep Dante alive in exchange for Fred’s life.
He then forces Dante to take a laxative in order to pass the watch, but the two are accosted by blood-drinking assassin Yendi the Vampire (Faisal Muhammed) (an assassin from Ghana who enjoys consuming blood), who Mike kills with his own machete. They travel to Mike’s headquarters, hoping to keep Dante secure, where Mike meets Siu-ling. Siu-Ling says she knows that Mike is an assassin and wants to join him. Mike fights Poco the Killer Clown (Beau Fowler) (a highly durable killer clown who carries a giant hammer as his main weapon) and kills him with one of Fred’s previously broken gadgets, while Siu-ling fights rival assassin Silas the Strangler (Peter Lee Thomas) (an assassin who prefers to strangle his victims to death) and strangles him to death with a heavy chain.
Dante manages to pass the watch before nearly being killed by swordsman Oyumi (Andreas Nguyen) (an assassin with Japanese origins whose fighting style is based on Ninjutsu); Mike challenges him to a hand-to-hand fight for Dante’s life, but receives a beating before Big Ray arrives and kills Oyumi with a shotgun. Ray attempts to kill Dante, but Mike convinces him to stand down for Fred and destroy the tracking device. Mike says that Ray brought him up, and so Ray is responsible for the way he turned out. Mike says that Fred is the only real friend he has in life and tells Ray that even killers need friends. Ray relents and asks Dante to clean up and change into one of Fred’s suits.
Mike, Ray, and Siu-ling transport Dante to Mrs. Zuuzer to exchange him for Fred; Mrs. Zuuzer orders Mike and Fred to leave the island, but Ray detonates an explosive that Fred had planted in Dante’s suit, killing Dante and Mrs. Zuuzer and earning them the 9-million-euro bounty.
Fred meets the woman he fell in love with online, but Mike explains that she left him after learning he was an assassin. In an ending voiceover, Mike tells the audience that the bounty allowed him, Fred, and Ray to set up a new assassins’ organization and move on to the next chapter of their lives, which he promises to be “a f**king Belter”.
Scott Adkins, Pat Mills, Stu Small