wizard thing. but if the stars align, the american film version of the girl with the dragon tattoo could become a blockbuster, and fans are finding the story behind the millennium trilogy as intriguing as the books themselves. in our number two story, nbc news s stephanie gosk goes to the source of the frenzy. stockholm. reporter: sweden has no problem attracting tourists. beautiful islands, beautiful people. abba literally playing in the streets. but this summer, tourists are flocking here for something else. millennium series madness. dragon tattoo book tours in stockholm are sold out. first page, second page, and it just, quick, quick, quick. reporter: swedish author steeg larsson s dark crime series has turned into a phenomenon. 40 million copies of the book have been printed worldwide.