'Highlander'  is a television series that is based on the movies of the same name. The series is set in the present day, in the Western  USA and Paris and it follows the life and exploits of the Highlander ; Duncan MacLeod.
Duncan was born in 1592, a little over 400 years ago in Scotland. He is a member of the Highland clan MacLeod. He is an immortal, who will never grow any older than he was on the day that he first died. He is also blessed with amazing healing powers, which heal his wounds within minutes.   ( This man never has a headache!! ) On the down side, because he is an Immortal, Duncan can never father any children. ( a shame and a waste of incredibly good lookin' DNA)
There are many other immortals throughout the world ~ some good, some pure evil. The Immortals battle against each other, and in the end there can be only one ~ he , or she  ( you go girls!), will gain the ultimate prize and the power of all the immortals who have ever lived. When they feel that the end is near, all immortals will feel drawn to a distant land, where they will fight for the prize. This coming together of immortals is known as 'The Gathering'.
The only way to kill an immortal is to behead them (ouch!). Most Immortals carry a sword, this way they will be able to defeat or defend against an assailant. When an Immortal is killed, the power of the decapitated Immortal passes on to the one who did the slaying ~ this event is called the 'Quickening'. The slain immortal's power is transferred amidst a great show of electrical surges and lightning. (which is really most impressive  ... and loud !! )
Of course, as expected, there are rules : No fighting is to take place on holy ground and all battles are one-on-one , with no interference...yaddah, yaddah, yaddah!

.... Oh, yeah and I really have to tell you about 'Methos' ( out of sight but never out of my mind!), the oldest living immortal , who is 5,000 years old ~ and baby, on him it looks good!!