Season 1 Episode 25
First Aired: July 19, 2011
Description: Close to cracking the case of what happened to the original Mystery Incorporated kids, the gang finds "The Obliteratrix" standing in their way. Now, up against this vicious undead assassin who's vowed to destroy them, the gang's only chance to solve the mystery and stay alive, and seek help from an old friend... H.P. Hatecraft.