IMDB’s description:
In the future, Highlander Connor MacLeod must prevent the destruction of Earth under an anti-ozone shield.
Let’s pretend Highlander II: The Quickening is a stand alone movie and isn’t a sequel to a Cult Classic.
The movie opens in the future setting of 1999. Apparently the Earth’s ozone is gone and people are dying by the millions, including MacLeod’s wife. On her death bed she makes him promise to stop that terrible burden on society called ‘The Sun’ no matter it what it takes. Flash forward a little bit and MacLeod (Christopher Lambert) is now leading a team of scientists. They appear to have successfully built a death ray to finally give the sun a taste of its own medicine. Oh wait, I guess it is a planetary shield. Well, same difference for the Earth.