Decepticons Underground is the tenth and final in the Ladybird Books series of Transformers storybooks.
- Cast (in order of appearance): Optimus Prime, Kup, Highbrow, Brainstorm, Quickswitch, Scoop, Quickmix, Fangry, Horri-Bull, Squeezeplay
Concerned with a lack of recent Decepticon activity, Optimus Prime has Kup arrange a series of long-range patrols to ferret out the villains. As the reports come back in with no success, it becomes apparent that there is one area of Nebulos that has not been searched – a mysterious region known as the "Nebulos Triangle," where electronics systems malfunction, and Nebulans have vanished over the years. Convinced that the Triangle is the location of the Decepticons’ base, Prime dispatches Quickswitch, Scoop and Quickmix to investigate.
When the trio of Autobots enters the Nebulos Triangle, they quickly lose control of their vehicle mode steering, and have to unsteadily continue on foot. They discover the ground to be metal underfoot, and follow a stream to a massive lake of mercury. While the two Double Targetmasters are left with no option to exit the Triangle to go around the lake, Quickswitch assumes his hovercraft form and heads out across it, only to wind up being sucked into a whirlpool.
Quickswitch finds himself in an underground cavern, but after exploring his puma mode, has to use his drill tank form to make an exit – an exit that leads him straight into the Decepticons' secret underground base! Quickswitch accidentally alerts the Decepticons to his presence when he bumps a stack of fuel containers, and flees to the surface, where he meets back up with Scoop and Quickmix. With the Decepticons hot on his tail, Scoop bulldozes the tunnel, collapsing rocks on the pursing Decepticons, which Quickmix then seals in place with a dose of concrete mixed from the mineral Nebulite. With the Decepticons contained, the trio head back to base to report to Optimus Prime.
- Amongst the patrols of Autobots sent out is a jet with Starscream's color scheme.
Items of note
- Dude, this book is about Quickswitch and the Double-Freaking-Targetmasters. That's an item of note right there.
- Visible members of the Autobot patrols include Grapple, Hoist (notable purely for being featured at a time so long after their toys had ceased to be available in shops), a fire engine that's either Hosehead or Inferno and Landfill.
- Quickswitch "hoses out Quickmix's drum". That sounds really dirty.