Cat (played by Donnie Yen) is a solitary and aimless contract killer who seems to live life on his own terms. Whether it's a rainy day or a sunny one, he always wears dark sunglasses, adding to his mysterious persona. Every night, he calls into DJ Simon's radio show, where he openly shares his thoughts and feelings, creating a strange connection with listeners. One of his nightly routines involves looking out his window at his "angel" who lives across from him, with whom he practices slow dancing in his imagination, as if holding onto a fleeting sense of love and companionship amid his dangerous world.
Meanwhile, policewoman Carrie (played by Annie Wu) is also an avid radio listener, often tuning into the same show and paying close attention to Cat's calls. Her goal is to eventually arrest the elusive killer, but her fascination with him hints at a deeper curiosity. Their paths cross unexpectedly when Cat is en route to meet a contractor, and he notices Carrie waiting for a bus. Curious, he strikes up a conversation with her, and they sit together on the bus. During their brief encounter, Cat hints at future meetings, telling her, "We will meet again."
When Cat reaches the contractor’s location, he agrees to take on one last job—an assassination assignment targeting Conroy Chan. The contractor warns him that Wesley (played by Jimmy Wong), a former partner of Cat's from when they were cops in New York, will be guarding the target along with other security personnel. This introduces a complicated history, as Wesley once framed Cat, leading to six years of imprisonment, making their encounter a tense reunion filled with unresolved conflict.
Cat successfully kills Conroy, but Wesley confronts him shortly afterward. A violent shootout ensues, where Cat shoots Wesley multiple times in the chest. However, Wesley survives because of his bulletproof vest and is taken in for police questioning. Wesley claims to have no knowledge of the killer’s identity or motives, which raises suspicions for Carrie, who is piecing together the puzzle. Meanwhile, Cat, in a rare display of vulnerability, attempts to assassinate Wesley using a sniper rifle. However, upon seeing Carrie talking to Wesley, Cat mistakenly believes she might be Wesley’s accomplice or girlfriend and kidnaps her. He keeps her at his house, surprised to learn she has been observing him from across her home and that she is actually a police officer.
Their relationship becomes increasingly complicated when Wesley calls Cat, leading to a tense exchange at a theater. During a chaotic sequence amidst gunfire, Cat passes Carrie a gun, indicating that she has helped him enough and suggesting she can now leave. When Wesley’s men arrive, Carrie helps Cat defend himself, shooting at their assailants with the gun she was given. In a surprising turn, Carrie reveals herself to be the police officer pursuing Cat—the man on the radio all along. Their confrontation turns into a moment of raw emotion, where they argue but also share a tender hug, hinting at a complex connection beyond their roles as cop and criminal.
The narrative takes a darker turn when Wesley captures Carrie’s close friend, demanding that she kill Cat to save her friend’s life. Faced with an impossible choice, Carrie hesitates before deciding not to kill him. Their dilemma is interrupted by a hitman, hired by the same contractor who hired Cat, aiming to eliminate him. Cat kills the hitman in a vicious fight, and in a rare and intimate moment, he and Carrie share a slow dance on a rooftop. During this quiet moment, Cat assures her he will do his best to save her friend before departing, leaving Carrie alone on the rooftop, torn between hope and despair.
Determined to rescue her friend, Carrie rushes to DJ Simon’s office, where she listens to Cat’s final radio call. She tracks down his location, gathering police backup for a confrontation. Meanwhile, Cat manages to kill Wesley and successfully rescues Carrie's friend. As Carrie enters the building to find Cat, she finds him in critical condition. She evacuates him from the scene, but tragedy strikes—police shooting leads to Cat’s death. The film concludes with Carrie visiting Cat’s grave, her grief evident as she reflects on the mysterious and troubled man who meant so much to her, forever changed by their fleeting connection.
