John Cusack leads an all-star voice cast featuring Jay Leno, Molly Shannon, John Cleese, Jeremy Piven, Steve Buscemi, and Jennifer Coolidge in this computer-animated comedy about a gifted scientist who happens to have been born with a most unfortunate deformity. Igor (voice of Cusack) may have been born with a brilliant mind, but unfortunately everyone around him is too distracted by his pronounced hunchback to notice. Forced to serve as a lowly lab assistant to nefarious scientist Dr. Glickenstein (voice of Cleese), Igor longs for the day he will become a mad scientist, take top prize at the Evil Science Fair, and finally win the heart of village vixen Gretchen. Every year, mad scientists from all of the local villages converge on Malaria to compete in the annual Evil Science Fair -- an event that always features an abundance of death rays, earthquake generators, and man-eating plants. This year, Igor's village manages to take the top prize, too. But despite the fact that his lab receives a substantial government reward, the king confiscates the invention to be used in Malaria's defense program. Unlike the other Igors, this hunchbacked genius longs to change the world in ways his master could have never imagined, and when Dr. Glickenstein dies just two weeks before the latest Evil Science Fair, Igor seizes the opportunity to shine.
Carefully covering up Dr. Glickenstein's death, Igor enlists the aid of angry brain-in-a-jar Brian and insecure re-animated rabbit Scamper to create an enormous, hideous creature of unparalleled strength. Trouble arises, however, when the creature turns out to be a female monster with a heart of gold. Unable to comprehend the concept of evil, the creature believes that Igor has named her "Eva", and longs for the day she will become a respected actress. With the Evil Science Fair fast drawing near, Igor has just two weeks to turn Eva the sweetheart into Evil the rampaging nightmare. Now, in order to win the competition, Igor works tirelessly to convince Eva that the Evil Science Fair is actually an audition for a twisted stage version of Annie, and that in order to win the lead role she must immerse herself in the evil character and never reveal her inner goodness. But as the "rehearsals" get underway, the nosy villagers come snooping around the castle, the malevolent Dr. Schadenfreude schemes to claim Eva as his own, and Igor slowly starts falling in love with his creation while realizing that life as a mad scientist may not be so glamorous after all.