It's Mavis 118th birthday and many of the most famous monsters are coming out for Mavis party at the hotel exclusively for monsters. Then a boy named Jonathan arrives at the hotel. Dracula (Mavis Dad) tries to get rid of him but then Mavis meets him and they ZING (like Love at first sight). Dracula then tells everyone Jonathan is the party planer for Mavis party. He dresses him up as Frankenstein so no one realizes that he is human. Jonathan and Mavis slowly become closer and fall in love.
In the end, Mavis and Jonathan go backpacking across the world. :)