It starts with fourteen year old Sonic the Hedgehog finishing up school. At fourteen, Mobians are allowed to drop-out of school and are given most of the freedoms of an adult. Sonic finishes the term (with detention on the final day) and decides he's never going back to school again. He doesn't know what he'll do now, but he plans on making a name for himself. Sonic wants to be the first Mobian to break the sound barrier on foot, which is an especially hard task because hedgehogs aren't known for their speed.
Speed and Purpose provides examples of:
- Accessory-Wearing Cartoon Animal: Justified in the case of Sonic; he doesn't see the point in wearing clothes like other Mobians, as he only needs his own fur for warmth, and his spines would rip them apart if he tried to wear anything more beyond shoes and gloves.
- Alien Sky: Mobius is an alien planet that has two moons.
- Ambiguous Disorder: Sonic has a short attention span, fidgets a lot, and has poor social skills.
- Amnesiac Hero: Sonic can't remember anything prior to age five. His earliest memories are nearly drowning and being found in Emerald Hill Zone.
- Anachronism Stew: It's mentioned in the first chapter that, until recently, Mobius was predominantly untapped wilderness with a few scattered high-tech cities.
- Book Dumb: Sonic doesn't do well in traditional classroom settings. He can't pay attention enough to study from books.
- Hold Your Hippogriffs: "Chaos meets chaos" is a Mobian equivalent of "birds of a feather flock together".
- Mistaken for Foreigner: Sonic mistakes Kintobor for an alien invader because he's never heard of humans before. Kintobor was actually born on Mobius.
- Oh My Gods!: Mobians use "Chaos" as the equivalent to "God".
- Parental Abandonment: Sonic washed up on Emerald Hill at age five. He can't remember anything about his past, aside from his name.
- Small Town Boredom: Sonic loves Emerald Hill but he also finds the Zone too peaceful for his liking. Nothing interesting ever happens in Emerald Hill.