A lawyer in his 30s named Danny still dreams about becoming a cowboy when his fiancée leaves him on the eve of their wedding ceremony. Fortunately, for him, not one, but two contrasting girls appear on his life to take her place: the bubbly Jo Jo and the more traditional Candice. But who will win out?

When beautiful Carla Purty joins the university faculty, genetic professor Dr. Sherman Klump grows desperate to whittle his 400-pound frame down to size and win her heart. So, with one swig of his experimental fat-reducing serum, Sherman becomes 'Buddy Love', a fast-talking, pumped-up, plumped down Don Juan.