The series will center around Ragnar Lothbrok (known to us from the Ragnarssona þáttr and other sources), who raided France quite successfully but met his end in England at the hands of the Anglo-Saxon king Aella. He is probably most famous for dying in Aella’s snake pit, playing a song ona harp with his feet (his hands were bound) before expiring. This led to his sons invading England with the Great Heathen Army, which is a tale in and of itself.
Some modern Heathens celebrate March 28th as his day of remembrance, as it is the anniversary of Ragnar’s sacking of Paris. Ah, good times.