It's 865 AD and the Great Heathen Army, the Vikings, have invaded Britain. Al takes up his sword to discover the truth behind how the Vikings were so successful in Britain. John Thomson represents the northern Viking horde as they explore the truth behind what Vikings really looked like, before they get ready for a Viking wedding. The pair delve into how these invasions started the north/south divide and set sail to discover the truth behind the Vikings' fearsome battle prowess, with help from British cultural historian Dr Janina Ramirez.