Former CIA spy Bob Ho takes on his toughest assignment to date: looking after his girlfriend’s three kids (who haven’t exactly warmed to their mom’s beau). When one of the youngsters accidentally downloads a top-secret formula, Bob’s longtime nemesis, a Russian terrorist, pays a visit to the family.
The movie starts off with a montage of fights and stunts from Chan's older movies including The Tuxedo and Operation Condor and then cuts to Bob Ho (Chan) waking up. The next shot features his next-door neighbors waking up, with Gillian (Amber Valletta) and her three children, Nora (youngest one and very girlish; played by Alina Foley), Ian ('geeky' and intelligent, played by Will Shadley) and Farren (stereotypical teenager and the oldest, played by Madeline Carroll) all experiencing a normal morning. The family has three pets which consists of a pig, turtle and a cat.Gillian strolls outside with her children to take the two older kids to school and Bob Ho, who supposedly works as a pen importer, spots her and helps her push down the trash can to the sidewalk. The two are shown to be romantic and the three kids are shown to be against it, due to them thinking he is nerdy and uninteresting. Later at night, Bob and Gillian are on a date celebrating their three month anniversary and although Bob tries to tell her that he's a CIA agent, his cellphone receives a message and he has to leave right away.Bob and Colton James (Billy Ray Cyrus) sneak into an American oil refinery and Bob catches the villains, who were trying to put a liquid into the oil supply. After returning to his work station, he informs he is retiring from being a CIA agent to finally settle down and live with his soon to be family. Bob begins removing his spy gear, but Glaze (George Lopez) tells him to keep his watch. Later, through the phone, Colton informs Bob that he sent files found in the Russian base to his computer.The following day, Gillian and the children visit Bob and informs him that her father was injured and needs his hip replaced so she'll be out of town and needs Bob to take care of the children for a few days. Though the children try anything to get out of the situation, Bob believes it'll be a great time to get the kids to like him. While Bob packs his items to go to Gillian's home, the children snoop around the house. Ian runs to Bob's Macintosh and finds a file he believes to be a pirated concert; using his iPod, he downloads it but it turns out to be the files that Colton had sent earlier, a formula to turn oil into dust.Meanwhile, Poldark (Magnus Scheving), the villain caught by Bob, escapes jail and returns to his minions. Poldark discovers his files have been taken and he tracks down the location to Bob's residence. Poldark and his minions set out to recover the files downloaded into Ian's iPod and to kill them all. While at a restaurant, Bob and the children are attacked by Larry (Lucas Till), a Russian spy, who attacks them with a knife, after having lied about going to university and being a poet. Bob fights him off and explains to the children about his true self and that he's a former CIA agent.Leaving the restaurant, Glaze appears and demands for the files with a gun. Bob knocks him out and runs away with the children in the car. In it, Bob discovers that the villains must have traced him with the watch Glaze told him to keep earlier and he leaves it in a rock in a desert. They escape into a hotel where Farren calls Gillian and tries explaining about who Bob really is and all the danger they've been in. Bob tells her to come pick up the kids right away. The next morning, all four go back home and Gillian yells at Bob and exclaims that their relationship is over.As he has unfinished business to take care of, Bob walks off being watched by Ian. Ian dresses up in a spy gear and runs out of the house on his bicycle preparing to assist Bob. Farren watches him go. Bob retrieves the watch and allows the villains to trace him to where he is, in an empty factory-like area. Ian shows up and due to him, the villains catch Bob and tie him up in a chair with Ian. The villains then remove the cameras placed around the place and Farren shows up tied up by Larry.After being interrogated, Bob discovers that it was Ian who had downloaded the files into his iPod at home. Most of the Russians hop on their vehicles to get the iPod, while Bob, with his spy ring with a razor blade, unties the three. The kids run to safety while Bob fights Larry, Glaze and Poldark with Ian's bicycle. After defeat, the two kids and Bob run into the car, take off and drive back home as fast as possible. After arriving, they discover Halloween is taking place.The three run home as the enemies run into the house from the windows and doors. Bob calls the CIA for help while he fights off all the villains, with help from the children. The CIA and Colton arrive right after everyone is defeated already and Ian gives his iPod with the files to Colton. After they all leave, Bob prepares to go home but after the children grow very upset, Gillian decides to stay with Bob. The two are later shown being married and Bob tells Gillian during the wedding that he has another secret to inform her; his real name is not Bob