Jacqueline Mackenzie, AKA Aero-Girl, is the daughter of the sworn protector of Foxbay, Battle Jack. She has recently begun her training as his sidekick, with the goal of one day taking over for him and accepting all the powers and responsibilities that come with the Battle Spirit (the source of Battle Jack's powers). Unfortunately, tragedy strikes and Battle Jack falls in battle against the evil Dr. Chimera, and the Battle Spirit is lost to Aero-Girl. Racked with guilt over her father's death, Jacqueline contemplates retiring Aero-Girl. The appearance of Jak-Jak, the gorilla who has somehow absorbed the Battle Spirit, pulls her out of her doldrums and together they seek to bring her father's killer to justice.