Harald Hardrada's path to becoming King of Norway ran through Constantinople, where Norsemen served as the Byzantine Emperor's personal bodyguards, secret police, and shock troops in the famed Varangian Guard. This film traces how these northern warriors ended up defending the richest city on Earth, and how Hardrada himself rose through their ranks before returning home to claim a throne and, eventually, die at Stamford Bridge in 1066. It covers the Guard's battle tactics in detail, including the shield wall and the aggressive wedge-shaped "bore snout" formation, and sets those against the wealth and excess of imperial court life that Norse mercenaries enjoyed far from the fjords. Historians and battle reenactments fill out the picture of a warrior culture operating at the edges of two very different worlds, Scandinavian and Byzantine, and the film builds toward the question its title poses: whether Hardrada earned his reputation as the deadliest Viking of his age.