Sylvain Marot, an inspector with the Paris police, is highly regarded as one of the most skilled officers in the French capital. However, after a scandal involving the Mayor’s wife, he finds himself reassigned to the municipal police in Marseille, where the mayor is none other than the former Commissaire Gibert. Sylvain's transition isn’t smooth; during a chase after a taxi driver, he inadvertently ends up submerging the patrol car, leading to a confrontation with the local police.
Under Gibert's direction, Sylvain learns of a notorious “gang of Italians” who utilize two high-powered Ferraris for their criminal activities. Faced with the inadequacies of local police vehicles, Sylvain understands that he cannot keep pace with the gang's fast cars. A colleague of his, Alain, shares stories about a legendary taxi from Marseille and its renowned drivers, Daniel and Emilien. Time has not been kind to them; Daniel’s taxi is now in Morocco, Emilien has left the force, and Daniel resides in Miami.
In a twist of fate, Sylvain and his team cross paths with Daniel's nephew, Eddie Makhlouf, who happens to be the taxi driver Sylvain was chasing. Sylvain presents Eddie with a proposition: if he can locate his uncle's taxi, he will be granted freedom. Eddie, however, makes a counteroffer, expressing his desire to become the taxi's driver once it is found. They eventually track down the fabled car, but it soon becomes apparent that Eddie lacks the same driving skill as his uncle.
With the operation "Mafia" set in motion, named by Gibert, the team begins their pursuit of the gang. An unfortunate misstep by Gibert leads to a disastrous accident, claiming the life of a Minister he had met earlier. As Sylvain pursues the thieves, he finds himself struggling to keep up. Recognizing the need for modifications to the taxi, he leaves it in the care of Eddie's sister, Samia, with whom he feels an instant attraction, though she is less than receptive to his advances.
Sylvain collaborates with Eddie to meet Rachid, an "Italian" who reveals the location of a training facility for the gang located at an abandoned racetrack. Sylvain and Eddie participate in a race and triumph. Afterward, Tony Dog, a former F1 driver and one of the gang members, offers Sylvain a job and invites him to an exclusive party. The entire municipal police team infiltrates the function, but during Eddie's undercover work as a waiter, he stumbles upon the gang's plans for their next heist: the theft of a diamond called "Cassiopeia."
When the duo overhears a conversation regarding corrupt city officials in collusion with the robbers, their luck runs out due to Eddie's blunders, leading to their capture. Sylvain manages to escape through a window, while Eddie is saved by an officer.
On the day of the robbery, the diamond arrives in Marseille via helicopter, but the robbers threaten to destroy it with a stolen military drone. After showcasing their destructive capabilities by blowing up police cars, they force the pilot to redirect the helicopter to a yacht. Undeterred, Sylvain and Eddie embark on a high-octane chase with the police. With Eddie’s friends distracting the corrupt officers, the municipal police commandeer a civilian vehicle in pursuit, although the gang continues their chase.
During the climax, as the robbers fire upon the taxi, Sylvain uses a boost feature to accelerate, resulting in the taxi flying off a cliff and crashing onto the yacht where the gang is hiding. The diamond is successfully recovered, and the criminals are apprehended. Sylvain attempts to find Samia to share the news, only to discover it’s already been reported on the news. Eddie appears on television, humorously disguised as a cop while making a proposal to his girlfriend.
Later, at a celebratory ceremony where everyone involved receives awards for their contributions, Sylvain arrives in a Lamborghini seized from the gang, followed closely by Samia in a newly built vehicle she had been working on. The two conclude the festivities with a race to the airport, marking a thrilling new beginning for them both.
