Dr. Zalost is the self-proclaimed "Greatest Unhappy Scientist who ever Lived", he lives in a giant, moving tower where he performs all of his research into the human emotions of misery and sorrow in order to find meaning in his otherwise miserable life. His latest creation however proves to be successful in his pursuit: Cannonballs that are able to control the emotions of others, if a person were to get hit by one of them, they would phase into the individual and instantly make them become miserable and saddened. Arriving in Nowhere one day, he asks the mayor of the town and his assistant to help fund his research by providing him with 33 and 1/3 billion dollars to help him, warning them that if they refused to comply, Zalost would run a field test of his unhappy cannonballs on their town. The Mayor and his assistant laughed at his threat and told them that he would be thrown in jail if he came back to fool them this way before kicking the scientist out of town hall.
True to his word, Dr. Zalost returned and began to lay siege to Nowhere with his unhappy cannonballs: making children stop skipping rope, chickens not wanting to cross the roads, and the cops and robbers to stop running and arresting. The mayor soon realized that Zalost was completely serious and gave him the money to fund for his research, yet it yielded no joy to him otherwise, claiming that people who are happy are also selfish: most likely attributed to how he can never seem to find any hapiness at all in life. Eventually, he discovers the existence of the Bagge Farm, who has completely avoided his assault on Nowhere, and proceeds to attack it. Zalost discovers that Eustace is immune to his unhappy cannonballs due to his generally miserable personality, but Muriel is hit by one of his unhappy cannonballs, and is reduced to an unenergetic old woman. Courage was forced to enter the tower to find the cure to the effects and save his owner. Dr. Zalost eventually managed to corner Courage and was about to drop him into the vat where his Unhappy Cannonballs spawn from, when Courage remembered that Muriels' Happy Plums were able to make anything happy; dropping a cup-full of them that he had into the vat, the concoction began to produce soft pink cannonballs that were able to reverse the effects of the Unhappy Cannonballs and return the people of Nowhere to their former happy selves again, and in the process destroy the majority of Zalosts' mobile tower along with all of his research. Narrowly escaping the explosion, Zalost saved one of his unhappy cannonballs to use it against Courage for foiling his means of finding meaning in his life; missing the dog and hitting Eustace (who was already nit by two unhappy cannonballs earlier, and turned him into a stone statue as a result of the third one), the unhappy doctor chased after COurage and a restored Muriel into their kitchen where he discovered a spoonful of Muriels' Happy Plums and ate it, the affects of the Plums managed to convert Zalost to make him happy as he always wanted. Zalost became a kind-hearted scientist and friend of Courage and Muriel, with his previously green skin and purple hair now turned into peach-skin and magenta hair due to his instant reformation.