Photographs, illustrations, and simple text describes the concepts of light and dark, how light can travel at different speeds, how a lens works, and how special types of light can be used.
Elderly Miss Ophelia, the prompter in a failed theater, collects shadows that do not belong to anyone and teaches them to perform the greatest comedies and tragedies of the world.
When Gustav convinces Fernie's safety-conscious father to enter the Gloom Mansion with Fernie and Perlie to help rescue Gustav's father from the Dark Country, there is a prison break from the Hall of Shadow Criminals, endangering them all.