As the the Dark Ages begin for Roman Britain, King Arthur's great-grandfather, Publius Varrus, and his British-born wife, Luceiia, struggle to build a crude hill-fort which they hope will help people survive these times. Known as Camulod, it will develop into Camelot. Publius has also crafted a one-of-a-kind sword called Excalibur, which will one day belong to his great-grandson, King Arthur.