Just when Chiro begins to understand the primate force, a planetoid is detected on a collision course for Shuggazoom and Otto thinks of ways to prevent the catastrophe.
Chiro's desire for an automated defense system to give himself a break from heroics backfires when three alien monsters slip past the system and threaten to destroy Shuggazoom City.
Chiro and Gibson infiltrate the Citadel of Bone to save their teammates from Mandarin and Sakko, and learn secrets about Chiro's past and Skeleton King in the process.