M is for... Mandragora

The Mandragora Helix was a vast spiral of energy which moved slowly through the galaxy, approaching Earth roughly every 500 years. Space travellers avoided it, and its true nature was unknown. The TARDIS was drawn into it in the late 1400's. When the Doctor and Sarah emerged they found themselves in a black void, surrounded by vast crystalline structures. They discovered that a powerful disembodied force inhabited it, as they heard a laughing voice boom out.

The Doctor quickly dematerialised - unaware that a fraction of Mandragora energy had stowed away in the TARDIS. This left the ship when it landed in the tiny Italian dukedom of San Martino. It had the power to kill by incinerating its victims. It found its way to an underground temple - home to an ancient Roman cult called the Brotherhood of Demnos. Mandragora had previously established psychic contact with its leader - the court astrologer Hieronymous. It gave him some of its powers, intent on using him to rule the Earth. Mandragora feared the future dominance of the human race and sought to prevent the planet developing beyond primitive superstition.

It later granted some more powers to the rest of the Brotherhood, as Hieronymous plotted to attack the new young Duke's accession masque, which was to have as guests many of Europe's most brilliant minds.

The Doctor employed a hidden metal breastplate to drain Hieronymous of his energies, then sabotaged the high altar with metal wire to drain and destroy the rest of the Brotherhood. Mandragora was ejected back into space, but the Doctor pointed out to Sarah that it would be in a position to attack Earth again at the end of the 20th Century.

Voiced by: Peter Tuddenham. Appearances: The Masque of Mandragora (1976).

• Tuddenham was billed as "Titan Voice". He is best known as the voice of the various computers in Blake's 7 - Zen, Orac and Slave.
• The Mandragora Helix never returned to menace Earth in the late 20th Century, but Russell T Davies provided a sequel of sorts with the Ancient Lights in the SJA story Secret of the Stars. He was going to make this explicitly Mandragora as it has the exact same scheme but then changed his mind, thinking the reference too obscure. And this from the man who featured the Macra in Gridlock...