Cornelius and Zula Crane were infamous as the Kraken and the Storm. Both sought power and yearned to rule the world. Everyone was aware of their existence and feared them, except for Commander and his wife Jetstream, who stood against them.

The renowned Strongholds superhero family is recognized for taking down Baron Battle and numerous other villains. Though they succeeded in finally defeating The Kraken and The Storm, they left behind a young girl—Cassidy Crane.

Unknowingly to most of the world, Cassidy Crane was the child of two prominent supervillains: The Kraken and The Storm. Though her parentage placed her under intense scrutiny, with constant prejudgment, she was determined to prove her worth. Cassidy's grandmother, Fiona Crane (Bloom), a renowned superheroine, became her advocate, dedicated to showing the world the truth about Cassie.

The renowned superheroine known as Bloom, took it upon herself to ensure her granddaughter's innocence was acknowledged when she enrolled Cassidy Crane in the exclusive high school, Sky High, where teens with special abilities are educated.