Unlucky in love, chemist Paul Matthews (Tate Donovan) visits gypsy Madame Rosa (Anne Bancroft) for help. Quickly realizing he is a hopeless nerd, she gifts him with Love Potion No. 8, which makes anyone who wears it irresistible to the opposite sex for four hours. Paul and animal psychologist coworker Diane Farrow (Sandra Bullock) decide to test it on themselves. The awkward pair suddenly find themselves alluring to anyone they approach, but soon realize they are most attracted to each other.