Salina is the lovely daughter chosen by her dying Celtic father to succeed her as the royal ruler in Roman-occupied Britain, just after the time of Christ, because she would be the moderate one among his daughters--not too militant or to soft--she would have the best judgment in dealing with the Romans. This is immediately compromised because the Roman ruler Justinian (played by Don Murray) and she quickly fall in love. Her affections for him are partially stirred because issues involving Roman rule include religion, rites, and taxes, and Justinian is fairer than other less virtuous Romans in his orbit in being accommodating. The Celts also acknowledge the protection the Romans provide against bandits etc. However, the Celtic Druids will not allow the marriage of Salina and Justinian.
Trouble is instigated by the bad elements of the Romans and Celts--led by Roman honcho Octavian and Celtic merchants whose taxes have been raised while farmers with bad harvests have been given relief. This has been done to draw off Roman forces (including Justinian) from the seat of government and split them up to quell the scattered Celtic attacks, while the intrigues of Octavian and his schemers are orchestrated, and they turn the queen and her coterie against the Romans. (Note a principal Roman administrator is named Tiberian--do up the aura with those imperial nomenclatures.)
"The Viking Queen" has good visuals, and offers the viewer its attempt to portray the customs, dress, and Druid religious rites of the Celts. However, the title is a mystery--actually, maybe not--it is more dynamic than "Celtic Queen." Anyway, the women were sometimes dressed (or pictured) in ways just short of "revealing." The chief disappointment is the ending. Viewers want a certain type of ending in this type of movie, but it wasn't to be, and is a letdown as entertainment. However, recommended otherwise.