It's almost Halloween, but the scariest thing in Room 26 has nothing to do with creepy decorations or spooky noises: Mrs. Brisbane is missing! This might be the biggest mystery Humphrey has ever tried to solve. Good thing he's SMART-SMART-SMART!

And the Case of the Missing Mrs. Brisbane is only one of the many mysteries Humphrey has to unravel!

Chapters:

1. The Case of the Mysterious Detective
2. The Case of the Missing Mrs.
3. The Case of the Mystifying Mr. E
4. The Case of the Curious Clues
5. The Case of the Afternoon Accident
6. The Case of the Baffling Ballerina
7. The Case of the Colorful Cards
8. The Case of the Mysterious Messages
9. The Case of the Problem Pupils
10. The Case of the Wandering Watch
11. The Case of the Creepy Classroom
12. The Case of the New Mr. E.
13. The Case of the Battling Boys
14. The Case of the Weird, Weird Witch