 Sherman Klump (Eddie Murphy) is engaged to his pretty girlfriend Denise Gaines (Janet Jackson), also a professor. But Buddy Love, his other him from the first movie, tries to stay in his own form for eternity, and therefore he keeps appearing, a thing that makes damage to Klump. Klump tries to destroy Buddy Love forever, but while his plan has failed, and he starts to lose his knowledge and memory, he must do something to prevent the lost of the thing that made Dennis fall in love with him - his wisdom. With the help of his very impolite and rude family, the Klumps, he tries to return his memory and to vanish Buddy Love forever.