The ending is exasperating, improbable, and painfully fun. To quickly summarize: Salander's super-eeevil father Zala shoots her in the head, and her half-brother Ronald Niedermann buries her, only to have a fox pee on her fresh grave. But wait, she's not dead, due to the type of ammo in Zala's gun! Using her late-birthday gift from Mimmi, a cigarette case, Salander digs herself out of her grave, and looks for gasoline to burn up her would-be murderers. But, she doesn't get to burn anything. Instead of going Firestarter, she goes Crime and Punishment, axing (but not killing) Zala and locking him in the barn.
Meanwhile, her knight-in-shining-Volkswagen, Blomkvist, encounters the terrified Niedermann fleeing on foot and promptly ties him up and leaves him on the side of the road. Blomkvist arrives at Zala's farm, finds Salander, and calls for help. Salander is barely alive; her brains are practically leaking out from her gunshot wound.
The last line of dialogue is Salander weakly speaking her rescuer's nickname: "Kalle Fucking Blomkvist" (32.185). Romantic? We're not sure. At least it's more happily romantic than the ending of The Girl With the Dragon Tattoo. At the end of Tattoo, Salander and Blomkvist are thrust apart by bad timing and some mutual misunderstanding. Here, they are reunited, though, admittedly, under some rather gruesome circumstances. So, don't expect any resolution of Salander and Blomkvist's feeling for each other, at least not in this installment of the trilogy.
The ending is also features quite the role reversal. Tattoo is devoted to Salander saving Blomkvist's life. She not only rescues him from the sadistic serial killer Martin Vanger, but, through her hacking skills, helps him restore his career and good name after he's found guilty of slandering corrupt financier Hans Erik Wennerström. (Wennerström is the guy Salander stole all her money from.) Finally, after almost a year and a half of searching for Salander, Blomkvist gets the chance to save her life. But, his job is only half done (her good name being in dire peril!) and when Fire ends, the story is only half told.
Things are far from neatly resolved. Salander is still wanted for murder and still public enemy number one. More importantly, she's still the enemy of Zala and company, the Secret Police, half of the non-secret police, her ex-therapist/nemesis Dr. Teleborian, and a gaggle of minor characters. Luckily, she's collected a nice assortment of people who are devoted to her and want to help her. So, expect some serious butt to be kicked in the next and final installment, The Girl Who Kicked the Hornet's Nest.