Two eleven-year-old misfits try to solve the mystery of a dead magician and stop the evil Dr. L and Ms. Mauvais, who are searching for the secret of immortality.
Cass and Max-Ernest discover the Museum of Magic, unscramble more coded messages, and solve new mysteries in their attempt to thwart the Terces Society's ambitions of discovering immortality.
As an evil dessert chef concocts a recipe for disaster in the form of a tempting chocolate bar, Cass and Max-Ernest attempt to stop an evil organization from carrying out its plot to gain immortality and wreak havoc on the world.
Cass finds herself alone and disoriented in a dream-like world, while back at home she is in the hospital in a coma with Max-Ernest desperately searching for a way to awaken her.
When a mummy disappears from the local history museum while Cass and her friends Max-Ernest and Yo-Yoji are there, they try to solve the case in order to clear their names and, they hope, discover the Secret they have been seeking.
