Weary of being alone in the vast forest, unicorn Amalthea (Mia Farrow) begins to wonder if she's the last of her kind. Following a rumor, she joins forces with feeblish wizard Schmendrick (Alan Arkin) and wayward barmaid Molly (Tammy Grimes) to look for the mystical Red Bull, a creature known to hunt and imprison unicorns. In order to walk unnoticed among men, Schmendrick magically transforms Amalthea into a beautiful woman. Together the three embark on a adventurous journey into the dark land of King Haggard, the man rumoured to control the Red Bull.