Billy Dilley’s Super-Duper Subterranean Summer

The Battle for Subterranea-Tania

As Billy, Zeke and Marsha prepare to leave Subterranea-Tania by throwing a "farewell party", Billy accidentally causes a robot-alien invasion led by an evil clone of Billy. The people of Subterranea-Tania then turn against Billy and it's up to the trio to try to stop the invasion once and for all.