1- A salesman takes advantage of unattended Dennis and tries to sell him a lot of shoddy-products, but Dennis is no fool and turns the table on the salesman by using the products on him. 2- While visiting Venice, Dennis and Gina pursue the crooks who stole the Mona Lisa and while in their hideout, switch the fake and real paintings thus foiling the crooks' plans. After a wild gondola ride the crooks are caught and Dennis and Gina are honored. 3- Falsely accused of eating all the chocolates, Dennis sets out to find the culprit. Having gathered all the suspects together on a stormy night, Ruff is discovered to be the guilty party.