Zhou Quan is a calculated hitman who, on a dark Shanghai night, takes the life of Wu Yanzhen after Wu phones his lover Zeng Jiurong — a moment that is unintentionally captured by a roaming civilian. In parallel, a down-on-his-luck extra, Chen Xiaomeng, teeters on the edge of despair and nearly ends his life, only to be saved when his phone suddenly rings with a chance for salvation. A chance encounter at a bathhouse becomes the fuse for a chaotic chain of swaps and deceptions: Quan, driving away from a police roadblock that turns out to be a film set, crosses paths with Xiaomeng, who is denied entry because his coupon expires at midnight.
Xiaomeng’s misfortune takes a sharp turn when he escapes with Quan’s locker key and the man’s belongings, including a surprising stash of cash. He uses the money to clear his debts and even to help his ex-girlfriend, who stands on the brink of remarriage. The plot thickens when Xiaomeng visits Quan in the hospital only to discover that Quan is suffering from amnesia and believes Xiaomeng is him. Seizing the moment, Xiaomeng adopts Quan’s identity, paying off hospital bills and stepping into his life as if he had always belonged there.
At the same time, Li Xiang, a successful author and CEO who is also a devoted single mother, arrives at the hospital when her 12-year-old son You collapses during a physical education class. You, anxious about a school speech about his father, insists that his father is an astronaut, a claim that makes Li Xiang’s day-to-day life even more complex. As Xiang navigates her child’s worries, a muddy puddle encounter splashes Quan, who is now mistaken for Xiaomeng, and Xiang offers him a ride to the apartment that Xiaomeng shares with Quan.
Quan’s life quickly becomes a patchwork of identities. He stabilizes the rent with Xiang’s help, notices the lifelines of Xiaomeng’s life in the apartment, and starts taking up Xiaomeng’s job as an extra, showing up on film sets with a newfound seriousness. Xiaomeng, meanwhile, learns to enjoy Quan’s luxurious surroundings, discovering outfits, a pistol, and a substantial payment for a past assignment. The two men collide again at Quan’s place, where Xiaomeng witnesses Quan’s stubborn honesty about his failures, and their uneasy collaboration deepens.
Xiang and Quan grow closer as she documents the amnesiac’s return to form and as Quan trains in the art of acting by studying films. She even enlists Quan’s help to steal an astronaut costume from the filming of The Wandering Earth so that You can deliver his school speech as if he were his father—an act that earns a standing ovation from the crowd. The night ends with Quan and Xiang sharing a vulnerable confession of love, and Quan accompanies her to a shoot where a sudden flash triggers a fragment of memory that threatens to restore his past.
As Xiaomeng digs deeper, he amasses more cash, giving it to Zeng Jiurong and warning her to flee an impending danger. He then confronts Quan to return his stolen identity, though You’s return of Quan’s notebook complicates matters. Wang’s underlings close in, forcing Quan and Xiaomeng to escape through a bathtub and rehearse a staged killing to keep Xiaomeng safe. The pursuit intensifies when You goes missing, prompting Quan and Xiaomeng to search and Xiang to disguise herself as Jiurong to mislead Wang.
A tense showdown unfolds: Quan reveals his true identity as Mr. Z and confronts Wang’s gang, wielding a knife, while Xiang’s quick thinking and You’s call to the police turn the scene in their favor. The enraged confrontation ends with a dramatic blow—Quan is stabbed, but the weapon proves to be harmless, and police intervene just in time. In the hospital’s quiet aftermath, Quan passes a keepsake to Xiaomeng, signaling a fragile truce between their intertwined fates.
The legal reckoning follows a sharp arc: Quan faces probation for fraud and identification forgery, while Wang receives a longer sentence for assault. Wu Yanzhen and Zeng Jiurong remain at large in the shadows of fraud, and the film closes with Quan’s release from detention and a hopeful reunion as Xiang picks him up and holds him close, suggesting a cautious step toward a new, more honest chapter for both men.
