Hagberg's writing style has been described as a cross between Tom Clancy and Ian Fleming. His thrillers generally feature a combination of technical detail, timely plots and super-spy heroics that are sometimes almost prophetic in their accuracy . In the novel "Joshua's Hammer", for example, written in 2000, Hagberg gives a chilling account of a mega-terrorist plot by Osama bin Laden to kill thousands of Americans on their home soil, published a full year before the World Trade Center Attacks. His scenario of McGarvey tracking bin Laden to his urban lair in Pakistan and shooting him in the head—far from Tora Bora’s caves—was described and executed in "Allah’s Scorpion" (2007) four years before the eerily similar event echoed Hagberg’s novel.