When Roman excels at his wizard lessons, Billie feels threatened and uses a Reverse Curse to slow him down, but it accidentally turns him into a baby.

When Billie's magic starts fizzling, she and Milo go to the wizard world for a cure; the family learns the true cause of her wonky magic: a power-draining Changeling!

When an oracle from the wizard world shows up on Billie's doorstep and predicts that Billie will destroy the big summer carnival, Billie stops at nothing to change the future.

When a new student arrives and takes an unlikely interest in Roman, Billie thinks she must be the Changeling and sets out to prove it.