I have never seen the movie, so I can only guess what it is about... 
Not wanting to go off topic, but maybe for others of interest too, here a brief summary of the animation movie:
The movie is about an unicorn which has recognized to be the last unicorn in the world. (BTW unicorns can only be recognized by those humans who believe -- for others they appear as normal horses.)
From a butterfly (if remembering correctly I assume it was a butterfly) she -- it's a female unicorn -- got the information that all unicorns had gone and had been captured by the red bull (
nowadays the term "red bull" got a totally different meaning ...
-- the movie is from 1982).
So she goes on a quest for seeking her fellows. On this quest she is guided by a magician (whose magic seldom works correctly) and a female robber. Finally the party found the other unicorns who a caught in the sea by the red bull on behalf of an old king who lives solely together with his heroic son in a cliff castle. To disguise from the red bull and King Haggard in highest danger the magician cast a spell on the unicorn to become a woman and with this is no longer of interest for the unicorn "hunters".
Although a love story between Lady Amalthea (i.e. the unicorn; in German Amalia) and king's son is in the offing, she still feels in her human body the soul of the unicorn wanting to free her fellows, but this desire got weaker more and more as long as she stays a human ...
Beautiful pictures, very atmospheric, and a great soundtrack by America.
Update: Oh, just realized that on wikipedia there is
more detailed review.
