I'd pick things up after Highlander should have ended.
Conner Macleod is an old man, with many children and grandchildren. He uses the Prize of Omniscience to run some kind of benevolent organization that has made the world a Utopia, but he's only mortal now and near death.
His children scramble to fill the void in his impending absence, but nobody will be able to run things smoothly without their father's supreme awareness. Ultimately, society will fall into relative chaos again. Conner is confident his kids will still be able to do a lot of good with his organization, but there's one son who isn't so sure. He is convinced the Prize needs to be reclaimed to save the world.
In his search to reclaim the Prize he'll earn more about the history of the Immortals and why they share this gift. The Prize is Omniscience, and its coveted by an ancient Evil. To keep it from this Evil, Omniscience is fragmented into Immortality, randomly selecting individuals with a recessive genetic predisposition.
So this great Evil, who supported the Kurgan the last time around, starts whispering in this Son's ear so to speak after he discovers the true nature of the Immortals. He convinces the Son to murder the Father in a ceremonial way so that the Prize becomes fractured into Immortality and therefore up for grabs again.
But the Son has been misled, he was told killing his father in this ceremonial way would transfer the Prize directly to him so that he could continue the Good Work. The ceremonial process allows the Great Evil to possess the Son completely, transforming him into another "Kurgan". Connor's children are the only new immortals at first, "new" random Immortals won't show up until after a full lunar cycle completes and a Global Quickening ushers in the new generation. So the trick is to kill Conner's children before the Global Quickening and regain the Prize.
The race is on, the Kurgan must kill the new Clan Macleod before the Global Quickening in order to quickly regain Prize without having to compete with thousands of Immortals all over the world. Can the Clan Macleod hold off the Kurgan long enough to ensure the greatest Evil ever known doesn't gain Omnipotence and therefore total dominion over mankind?