When Mrs. Cakel transforms from a rampant rule-enforcer to a quiet excuse-accepter, Danny and Calvin begin a secret investigation and encounter a variety of mysteries along the way.
Danny and Calvin decide to find out why their fourth-grade teacher, Mrs. Cakel, is suddenly behaving very strangely by not only failing to enforce her many rules, but by violating some herself.
When Mrs. Cakel transforms from a rampant rule-enforcer to a quiet excuse-accepter, Danny and Calvin begin a secret investigation and encounter a variety of mysteries along the way.