The Diabolical Masterminds of Series 6 (1968-9)
Russian assassins led by Ezdorf, captured years earlier when it was discovered they intended to kill secret service agents, all mysteriously vanish from their prison cells, as Russian scientist shave devised a chameleon liquid which lets the users blend into the background. Daft, isn't it?
Speaking of daft! An inventor creates a self-propelled electricty-consuming box that kills by electric discharge. God knows why, as they seem hideously suceptible to being shorted out by water, or overloading by high voltages. His invention is stolen by Kruger, who plans to decimate Britain by letting thousands of the boxes loose on the country.
The unhinged and greedy Lasindall brothers, desperate for their father's hidden riches conspire with their housekeeper to kidnap Tara when they discover she is the spitting image of their father's lost love, Pandora. They drug Tara and try to condition her to think she is Pandora, and living in London in 1915 but their eagerness gets the best of them and the riches - a Rembrandt hidden under another painting - is destroyed.
Tara apparently witnesses Mother's murder from a terrorist bomb in Steed's flat, and her 'rescuers' want her to identify Steed's hideout as he's next in line for assassination. She believes the crowd of military and medical personnel around her until her cast accidentally cracks open, and the race is on to reach Steed before the villains can find him from her confused description.
Grenville plans to (can you guess?) prevent world peace by disrupting a major peace conference - this time with a missile fired from a nearby country house. He gets his decidedly strange medical expert, Circe, to implant phosphor bombs in the occupants' necks, after testing this horrible device on an innocent man. However, he didn't realise the occupants were personal friends of Steed and Steed's resolve and Tara's timely arrival sees the end of their plans.
Jay Fairfax plans to destroy confidence in British Security by... (no! no! not doubles, or Steed being suspect this time!) ... by making Tara appear to be a traitor trying to destroy the War Room computer system. She's sent presents by the other side's Colonel Zaroff, is caught smuggling film out of the War Room and framed for a murder, leading to her security rating being stripped and orders given for her immediate arrest, but she convinces Steed of her innocence, and he convinces Mother, and they converge of Fairfax's gymnasium to stop the villains escape.
Psychiatrist Dr Jaeger is hired to wipe out the board members of Tobias' company, by brainwashing other employees to kill their bosses. That's about it, really.
The 'Master' devises an escape route for embezzlers and other white collar criminals by faking their deaths (using a serum that temporarily arrests all body functions) and having them buried in a graveyard which is in fact a huge underground resort where the absconding fat cats indulge in an orgiastic life of food, wine and girls before Steed and Tara dig out the truth and lead them all back to the land of the living.