Victor Maynard, portrayed by Bill Nighy, is a highly skilled assassin leading a solitary existence, deeply rooted in his family's legacy of professional killing. He carries out his assignments with remarkable efficiency and a complete absence of guilt. One fateful day, after successfully eliminating a target, he faces an unexpected moral dilemma when it comes to killing the pet parrot, Roger. Instead of ending the bird's life, he decides to take Roger as a gift for his mother, Louisa, played by Eileen Atkins, a stern woman who has been living with him until recently. In a surprising birthday gesture, she presents Victor with a leather-bound book filled with news clippings of his kills, from the very first one to the latest, leaving blank pages for future assignments. Additionally, she expresses her worry about his lack of a successor, questioning whether he might be gay.
Enter Rose, a character brought to life by Emily Blunt, who has a knack for stealing. In her latest heist, she successfully sells a forged Rembrandt painting—crafted by her friend from the National Gallery—to Ferguson, a character played by Rupert Everett, for a whopping £900,000. However, when Ferguson uncovers the fraud, he hires Victor, the renowned hitman, to eliminate Rose. Victor accepts the job and begins his pursuit of her, yet time and again fails to carry out the hit, culminating in a disastrous moment when he accidentally shoots a random shopper in a fitting room instead.
To get closer to his target, Victor sets up surveillance equipment to monitor Rose’s activities but ultimately dozes off during the chaos of her romantic encounters. The next day, he awakens just as she departs, leading to another missed opportunity. Frustrated, Louisa implores Victor to make amends with his employer and offer to complete the assassination pro bono.
Eventually, Victor spots Rose in a parking garage, where he witnesses another assassin preparing to kill her. He takes decisive action, eliminating the rival hitman before being confronted by Mike, another assassin hiding in Rose’s car. In a twist of fate, Tony, an apparent vagrant played by Rupert Grint, inadvertently saves Victor and Rose by picking up Mike's discarded weapon, quickly impressing Victor with his audacity. However, Victor sends Tony home and makes his escape with Rose, leading to a chaotic situation where Mike pursues them after a violent altercation.
In the face of impending danger, Rose offers Victor a lucrative protection deal, mistakenly believing he is simply a private investigator. They check into a luxury hotel to evade their pursuers, only to find themselves mistakenly situated on the same floor as Ferguson, who subsequently hires Dixon, another lethal hitman, to eliminate both Victor and Rose. As Victor navigates a series of close encounters, he must grapples with threats from both Mike and Dixon, leading to a frantic hospital visit after a high-speed chase.
The trio eventually finds refuge at Victor’s serene countryside home, where he takes Tony under his wing, mentoring him in the guise of "private detective" work. However, danger looms closer as Louisa makes an ominous return to finish what Victor couldn’t. After a heated confrontation, Victor, Tony, and Rose bond over shared experiences, leading to unexpected romantic developments between Victor and Rose.
As their relationship flourishes, Victor begins to shed his solitary ways, but Rose soon discovers the truth about her being a planned target for assassination, leading to distrust and chaos that ends with brutal confrontations involving Louisa and Dixon.
Fast forward three years, and we discover that Victor and Rose have forged a new life together, now married with a child named Angel, while Tony has moved in with them. One day, as they play outside, Tony comes looking for the family cat, only for them to find little Angel patting dirt into the yard, hinting at a darkly comedic twist on their shared past. Victor watches the scene unfold with a proud smile, capturing a moment of twisted family bliss.
