It's the second semester at Gotham Academy, and everything is back to normal. Of course, "normal" for Gotham's top prep school would be considered uncontrollable weirdness anywhere else! First, a bunch of students start walking out of their extracurricular activities with no explanation and signing up for a strange new society--Witch Club! Then, a stolen map of the Academy puts the students on a trail of ancient symbols and hidden chambers. There's plenty for the Detective Club to investigate--but Olive Silverlock is distracted by her new rebel roommate, Amy. Is Maps Mizoguchi right to be suspicious of a bad influence, or just jealous that she's losing her best friend? Plus, Detective Club is joined by the world's greatest detective--Batman!