The Case of the Missing Shoe A mystery is a narrative that presents itself as a puzzle or unknown element, with the pursuit of answers that unravel the enigma at its core. Savannah's characters are at their finest in this new Mystery series of stories about the colorful, imaginary, friends of a young girl, living on the Autism Spectrum. The Autism spectrum disorder (ASD) is a term for a group of complex disorders of development. These disorders are characterized, in varying degrees, by difficulties in social interaction, verbal and nonverbal communication and repetitive behaviors.