After Grace Wong sends her daughter to school, her car is knocked down by another vehicle and she is abducted from the scene. The kidnappers, led by Fok Tak-Nang, return to Grace's house, where they kill her maid, and start searching the place. Grace is then taken to an abandoned house, where she manages to repair a destroyed telephone. With the phone, she manages to contact Bob, a single father and debt collector who has promised his son, Kit-Kit, and his sister, Jeannie, that he will meet them at an airport, before Kit-Kit boards a flight to Australia.While talking to Grace on his cellular phone, Bob agrees to help Grace and hands his phone to patrol officer Fai, who believes that the distressing phone call is a prank, due to Bob's reckless driving. Grace is interrupted from the call when Fok and his men enter the room, having abducted her brother's friend, Joe. Fok forces Grace to contact her brother, Roy. After listening to Roy's answering machine, Fok kills Joe and leaves with his men, now planning to go after Grace's daughter, Tinker. Grace persuades Bob to head to the school and find her daughter before Fok's men do. When Bob arrives, he is distracted by the school's headmaster, and minutes before the school's class dismissal, he finds Tinker too late, as she is abducted by Fok's men. Bob goes after the abductors, but winds up losing sight of them in the struggle. After crashing through a truck, Bob later finds a handgun left in his car by a fellow debt collector.Realizing that his phone has a low battery, Bob heads to a phone store to buy a cell phone charger. After losing his patience with the flirty service clerk, he holds the store at gunpoint and pays for the charger. After Bob is caught on camera at both the school and the phone store, Detective Fai heads to Grace Wong's residence. He is still convinced that the kidnapping situation is a prank, having talked to Michelle, a woman impersonating Grace. Fok decides to go after Grace's brother, Roy, who is in a hospital.Fai decides to call Grace's house, after realizing the real Grace Wong is a Mandarin-language speaker, while the impersonator he met speaks Cantonese. At the hospital, Bob manages to distract Grace's abductors, who are revealed by police to be Interpol agents. The agents, however, manage to successfully kidnap Roy and take him to a hill where he has hidden a camcorder. Bob intervenes, grabbing a hold of the camera and fleeing from the agents; unfortunately, he loses connections with Grace.Fai heads to Grace's house, where he confronts and kills Michelle, realizing she was also an Interpol agent working for Senior Inspector Fok. As Grace tries to contact Bob, she is caught by one Fok's henchmen. Grace kills the henchman and manages to find her daughter. However, while planning to escape, Grace and Tinker are caught by Inspector Fok. Bob looks at the evidence on the camcorder. The footage, captured by Roy, reveals Fok brutally executing several American drug dealers and stealing the drugs. Bob calls Fok, and tells them to meet him at the airport in an exchange for the evidence and the hostages, while attempting to keep his promise to his son.At the airport, Bob's plans to meet his sister and son are foiled as Fok is conveniently between them and Bob's hiding place. After telling Fok to go towards the parking lot, he demands that Grace, Roy and Tinker be released. They flee to a patrol car that is also in the lot. Unfortunately, Bob is caught by Fok and his men, and fights against them until Fai catches up to them. Fok and his men are arrested by Detective Cheung and his Serious Crimes Unit. After Bob hands the videotaped evidence over to Detective Cheung, Fok and Tong, one of Fok's henchman, appear, and Cheung reveals that he was working with Inspector Fok. Fok deletes the footage on the videotape, and a violent confrontation ensues in a loading dock in the airport where Fai and Bob take on Fok, Cheung and the corrupt Interpol agents. Detective Cheung is shot to death by Fai after attacking him with a forklift truck.Bob confronts Fok on a scaffolding. After Bob reveals he still has videotaped evidence on his cell phone and threatens to send it to the police, Fok kicks Bob off the scaffolding. A net manages to save Bob's fall, but sends Fok falling to his death. While this was going on, a member of Fok's team rekidnaps Grace and her family and prepares to kill them, but Grace manages to defend her family long enough for the police to arrive. When Bob returns, Fai talks to him, feeling the glory he once had as a police officer, and wishing that they never meet again after their ordeal. Bob then meets Grace for the first time in person. Grace thanks him, and Bob concludes their meeting by saying, "If you're gonna call for help, no thanks! If you want dinner, then I'll consider." Bob is then reunited with his son, who is happy that his father kept his promise.
Output: Question: who led grace's kidnappers?, Answer: Inspector Fok