Danger Mouse is fired by Colonel K after destroying the whole of London and bankrupting the Secret Service. He is immediately replaced by mechanical Safety Mice invented by the reformed Baron Silas Greenback.
Penfold insists on a mission free holiday, so DM agrees to go on a cruise. But Baron Greenback has made a machine that morphs ordinary sea creatures into terrifying sea monsters and holds the world to ransom.
While Professor Squawkencluck is away at the Chicken's of Rock Festival, a small plant in her laboratory grows into a Vicious Scrub and engulfs the entire world because Danger Mouse insists on taking care of it.
After visiting Professor Squawkencluck, a girl called Dawn's tiara gives her special powers. Danger Mouse must embrace his feminine side to stop the pink-obsessed supervillain, the Princess, from turning the whole world girly.
Fed up with Danger Mouse always breaking her gadgets, Professor Squawkencluck has invented HEAD (Headquarters Electronic Assault Defender) security system. But 'Big Head' soon starts to take over all security of Great Britain.
Red traffic lights pop up all around the world, stopping everyone and everything in their tracks. It's all part of Baron von Greenback's plan to stop the Earth spinning, causing everything to float into space due to a lack of gravity.
Greenback has stolen a Tectonic Plate Spinner from the U.S. government that can move an entire country to a different location with the touch of a button. Danger Mouse has to work together with his female American counterpart, Jeopardy Mouse.
Back in 1983 or thereabouts, Agent Danger K defeated Bert Bad Boy, who threatened to destroy the UK with his dreadfully rude behavior. Now, Bad Boy escapes from Arkwright Asylum, steals his megaphone from the top secret Danger Museum and attempts to complete his original plan, but this time expanded to include the entire world.
A colossal meteor is about to destroy the Earth. Professor Squawkencluck proposes to use her Schrinketizer invention to reduce the meteor in size. But the combination of Penfold's inability to catch and Isembard King Kong Brunel's determination to get his hands on the device causes disastrous results.
After all the other Danger Agents, and Penfold, become super-intelligent, as a result of eating brainpower-enhancing celery, Danger Mouse considers looking for a new job. However, there is a little hitch in the celery, as Nero, on Greenback's orders, snuck into HQ and his DNA polluted the gene pool.
Penfold's addiction to social media helps the Baron turn all of DM's secrets against him in order for him to use Big Ben as a diamond-tipped drill to ball through the Earth for the tonnes of gold, in the Earth's core.
Danger Mouse's confidence takes a hit when the Baron accidentally steals it and invigorates his shy daughter, Delilah von Greenback, to create a criminal mastermind! But unfortunately, his plans backfire when she wants to become an evil mastermind herself! Can "The Scrapbook of Momentous Mouse Moments" help DM find it within himself to fight back, or will Delilah make her own planet of planets, called "Delilahiana".
It's Crimicon - the Annual Criminal World Convention - and DM and Penfold are joined by a brand new secret agent, named Agent 58, to stop Isambard King Kong Brunel from selling a potentially catastrophic custard bomb doomsday weapon. But, unfortunately for them, he's sold it to Baron von Greenback!
DM and Penfold go back to school to thwart the plans of an evil food scientist, named Professor Ham Hands and his killer hot dogs. Also, Danger Mouse needs to pass his final science test or his spy license will be revoked.
Danger Mouse encounters his toughest challenge of the series as maniacal trillionaire Augustus P. Crumhorn IV, known as Crumhorn, his last name, releases every enemy DM has ever battled. Once all the villains are defeated, except for the Princess, he and Penfold go after her and DM fights Crumhorn. While fighting Crumhorn, he gets zapped by guns and lazers. Has the world's greatest secret agent survived this epic battle with Crumhorn and been buried under the rubble, or is this the end of Danger Mouse as we know it?
Penfold and Crumhorn find out that Danger Mouse is still alive, but is lost in a jungle. Penfold sets out to rescue him while Crumhorn is set on destroying him. When they arrive, they find out that DM has amnesia and can't remember anything so he can't stop Crumhorn leaving the rest of the agency to stop him. Can Penfold, Professor Squawkencluck and Colonel K stop Crumhorn, will DM get his memory back or will Crumhorn take over the world?