Ghosthunters #4: Ghosthunters and the Muddy Monster of Doom!

Intrepid ghosthunter-in-training Tom has battled Incredibly Revolting Ghosts, Gruesome Invincible Lightning Ghosts, and a Totally Moldy Baroness. But, as it turns out, nothing — nothing — is more frightening than...final exams.

To earn his Ghosthunting Diploma, Tom has to nab a Deadly Messenger, the hardest ghost of all to catch. While on the hunt, he stumbles into the yucky, mucked-up lair of a mud-dripping minotaur demon who has assembled a ghoul army with the goal of world domination. Suddenly there's a whole lot more at stake than Tom's graduation: This is one test the team can't fail!