Can it be so? Is Mr. Weatherbee really leaving his post at Riverdale High? It appears so, and while his replacement, Mr. Bartlett introduces himself as a pal of a principal, it soon becomes apparent that he's piranha in disguise! With both students and faculty caught in the crossfire, there's nothing else to do but form an alliance to try to get Weatherbee back! 'Summer Spirits': When all the electrical machines in the school start operating by themselves, Mr. Flutesnoot is convinced the school has been haunted. It will take a man of science to solve this mystery, so get going, Dilton!