"Mikael Blomkvist is a graduate of the School of Journalism and had much of his professional life dedicated to revealing and report suspicious transactions, specifically in the field of banking and business," writes Larsson in the first volume of the trilogy.

At the start of The Girl with the Dragon Tattoo, he loses a libel case involving damaging allegations about billionaire industrialist Hans-Erik Wennerström, and is sentenced to three months in prison.

At the end of the first novel, Salander saves Blomkvist from Vanger's great-nephew (and Harriet's brother) Martin, a serial killer who has been murdering women throughout Sweden for decades.

With the information uncovered by Salander, Blomkvist publishes an exposé article and book that ruins Wennerström, clears his own name, and propels his magazine to one of the most respected and profitable in Sweden.

He eventually discovers that the murders are part of an elaborate conspiracy between The Section—a faction of SÄPO, the Swedish Secret Service—and Salander's father, former Soviet spy Alexander Zalachenko, whom The Section had illegally helped to defect.

He also learns that Bjurman had raped Salander a few years earlier, and that The Section conspired to have her committed to a mental hospital as a child in order to protect Zalachenko.

In the final novel of the original Millennium trilogy, The Girl Who Kicked the Hornets' Nest, Blomkvist risks his life researching the full extent of SÄPO's crimes, and persuades his sister Annika, a lawyer, to represent Salander, who has been cleared of the original murder suspicions, but is now charged with attempted murder and two cases of grievous bodily harm, as well as several other offences including possession of illegal weapons.

With help from government prosecutors and Salander's fellow hackers, Blomkvist finds proof of the conspiracy and publishes an exposé article on the case, which results in several SÄPO agents being arrested.

She had found out that a criminal organization called "The Spider Society" stole the data with help from Solifon employees and a mole in the National Security Agency.