Detectives from 4A. Cheerful Zombies and Alien Secrets

What secrets does Pechenkhin keep and why does the whole school consider him a traitor? Who will win the comic contest about cheerful zombies? How to unveil the invisibility of Mayakogradov? Will Andrey Svetlyachkov complete the mission "March 8" and be able to overcome his fear of public speaking?

The detectives from 4 "A" will face complex cases and unexpected turns!