On her 15th birthday, Susie must prepare for her Gibbous Rite Ceremony. Will Mildred be able to keep her chaotic magic in check for just one day so Susie can become the full witch woman of her dreams?

When Oscar isn't invited to Alexa's birthday party, Mortimer tries to make him feel better by telling him about a similar time in his life. Ever the glowworm, Oscar sneaks back in time to help a young Mortimer overcome the sad experience.