Shaw, the bad guy, needs just one final part to build and sell his super weapon. Hobbs' team work out that his target is going to be in Spain.
Meanwhile Brian returns to the US and asks a favour from his old enemy and rival Fed, who agrees to put his job on the line for some unknown reason. So Brian is arrested under a different name, and taken to the same jail that holds Braga - the drug baron from Fast 4. Brian hits the other Fed so he's kept in solitary next to the baron.
Braga has rigged the system so the electrics are cut, and with two bodyguards they enter Brian's room. As in every James Bond movie, Braga reveals all his plans to Brian as he thinks he is a dead man anyway. We learn that Shaw has been going for years and is at the top of his game (even though he just looks to be in his mid 30s), and has everyone in his pocket. He knew Letty was undercover, and tipped off Braga to kill her.
The car explosion knocked Letty unconscious, and she has completely lost her memory, so she hasn't been faking it.
Brian knocks out all three men, and gets back to his team in Europe. He apologises to Dom as he knows it was his fault about Letty, but to be honest for all that hassle, was the trip really worth it? He doesn't even tell the others that the bad dude thinks he's one step ahead until later.
Hobbs is at the facility that holds the weapons part when one of Shaw's men breaks in. They fall for the trap and put a convoy in place to move it. While on the road, Shaw's men strike. Dom and Brian have figured this out, and ride onto the scene with fast cars to take on an army convoy.
They don't help too much at all. The convoy had a tank inside a truck, for some reason, which the bad guys drive out and start to cause carnage on the roads, killing many motorists it seems.
Dom and Brian manage to wrap a steel cable around it. Shaw throws out Letty, and Dom must jump across the motorway gap, high above a huge ravine, to catch her and save her life.
The cable wraps around a bridge column and holds, flipping the tank.
In custody, Shaw says he has an offer for Dom. They phone a number and listen to Mia, who has been tasken hostage. The base captain laughs at the attempt to bribe them. Suddenly Hobbs pulls out a gun and tells them that all the bad guy's team will be allowed to go free, as it's not fair to mess with someone's family(!)
Shaw asks his girl to follow him - and of course Hobbs' right-hand girl Riley follows him.
Outside, Shaw tries to phone his men to kill Mia anyway. Ludacris blocks the cell phone transmissions - which they could have done anyway. They chase after Shaw, when suddenly a giant Hercules plane approaches the runway. The doors open and all the people driving a range of vehicles fight it out to get onboard.
Dom, Letty and Brian make it on board with Shaw, the really big bad dude and a few already hitching a ride, including Mia. Mia is soon rescued. The fight goes on for a long time - it's literally meant to be a 50mile straight runway.
Hobbs knocks out the big dude, while Dom defeats Shaw. Letty defeats the tough girl. Brian rescues Mia, being chased by Shaw's chick in the super -powered Mariokart. Brian tricks her and she ends up running over a barrier, flipping the car.
Meanwhile, to stop the plane taking off the others fire hooks into the wing flaps. Han's girl falls from the car as it starts to take off, taking her own life to get some shots at the saboteur from before. It doesn't work as he's still alive, but Han finally finishes him off.
The plane is being dragged back, and starts to burst into flames. Letty and Hobbs jump to safety. The plane crashes when Dom erupts from the front in a fast car.
Later, they're all relaxing back in the US at Dom's old home. Han is a little despondent, as you'd expect. Letty doesn't have her memory back but is pleased to be home.
After the credits, Han is being chased around Tokyo in an RX-7. He crashes, in a similar scene to F&F3. Jason Statham walks up to the car, and shoots him. He then phones Dom to say he's taking out his team, one at a time. The RX-7 explodes. but like F&F3 (and Letty in Fast4) he'll probably be back as these good guys never die.