Mary Stone was a biochemist.

She was the sister of Jeff Stone and Andy Stone.

Mary, Andy and Jeff resided in New Paris, Venus, but were on holiday in the planet's Churchill Mountains when the Daleks attacked in 2400. Jeff and Mary were captured. (COMIC: Invasion of the Daleks)

She was put to work at an oil well, where she convinced the Daleks to allow their slaves a rest period. She was then taken away to implement her plan at the other oil wells. (COMIC: The Oil Well) She was later put to work at the Daleks' base under the Churchill Mountains until she was freed by Andy and Jeff. (PROSE: The Secret of the Mountain)

Mary and Andy were later captured by Daleks on Gurnian and forced to approach a group of Horrorkons, which they later used to defeat the Daleks. (COMIC: The Humanoids)

On Jupiter, she developed a new form of acid which ate through Dalek casings. (PROSE: Break-through!)

Later, she and the other Stones discovered and defeated a Dalek plot to destroy Earth. (COMIC: Battle for the Moon)

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