In this pilot episode, Danger Mouse and Penfold are dispatched to Loch Ness to investigate the theft of bagpipes and increased activity of the Loch Ness Monster. They uncover a plot by Baron Greenteeth (known in later episodes as Baron Greenback) to find "The Lost Chord," a musical note capable of causing great destruction.
Baron Silas Greenback unleashes robots of destruction of increasing size against Dangermouse, the greatest guardian of peace and justice in the civilized world. First, a duo of Sniver Snappers are delivered to DM's secret hideout. Next, Penfold is almost stomped by a pair of electronic boots. Finaly, Dangermouse comes face to faceplate with Big Tom, The Mouse Masher.
Baron Greenback plans to take over the world by combining the sound of 10.000 stolen bagpipes he has hold up in Castle McStrangle. Luckily, Dangermouse has a good set of lungs up his chest. That is, of course, as long as he and Penfold survive the attack of a mechanical Loch Ness Monster.
Baron Silas Greenback takes Colonel K hostage. Greenback makes the Colonel contact DangerMouse by videophone. As part of Greenback's elaborate ruse, Colonel K tells DangerMouse that Greenback is in jail, and that DangerMouse and Penfold should go on holiday. The Colonel sends DangerMouse and Penfold to a castle in Transylvania. At the castle (owned by Greenback), the villain attempts to terrify the visitors using remote-control robots dressed as ghosts, mummies, et cetera.
Baron Greenback has stolen Heinrich Von Squakenkluck's secret serum to create giant super duper chickens and has let one loose in the heart of London. Dangermouse and Penfold have to stop the Baron with a little help from Flying Officer Buggles Pigeon.
The greatest evil genius the world has ever known, Baron Silas Greenback, plans to 'borrow, the hardest diamond in the world, "the Eye of Hercules". For with it attached it to his atomic powered mega drill, he can tunnel right into the bank of England. To make sure Dangermouse won't stop him, he has already dispatched his latest invention, the 'Martian Mouse exterminator' to get rid of DM.
Baron Silas Greenback has created a dream machine. The device resembles a colorful cloud. The dream machine descends upon DangerMouse and Penfold. They see no possible escape. Within the dream machine, whatever Penfold says is created. Terrified for a few minutes, DangerMouse and Penfold find a way to create just what they need to confront and defeat the villainous Greenback.
20.000 elephants have been turned into sugar-cubes by evil mastermind toad Silas Greenback. They only revert back to their normal size when dropped into a cup of tea. Dangermouse and Penfold travel to Africa, where an encounter with all the wild animals causes Penfold to revert into some bumbling kind of lord of the jungle.
The world's top men are laughing themselves unconscious thanks to Baron GB's microscopic Gigelacockos germs that are spreading via telephone lines. Dangermouse, the white wonder and his trusty assistant Penfold race to save the British PM before the Baron and his crow henchmen can fire his Gigelacockos cannon all over London.
Arch villain Silas Greenback has perfected his intergalactic traveling machine. Using Penfold as bait, the worlds most evil toad lures Dangermouse into his trap and boldly blasts him deep into time and space, towards a planet ruled by talking machines.
The rotation of the world is slowing down. So, DM immediately heads for the North Pole, where Baron Greenback is attempting to hold the world to ransom by stopping the world with a anti gravity rotation retarder of some sort.
Pyramids have been popping up all over London. It will take only twenty more to sink the whole country. So, Dangermouse and Penfold set forth for Africa, specifically the Saharah desert. After all, the sand the pyramids are made off must have come from somewhere.