Missy will step up her game as Doctor Who enters season 9.

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The latest iteration of the Master caused chaos in "Dark Water" and "Death in Heaven," and it appears the dastardly Time Lord will be up to her old tricks in the upcoming premiere.

In fact, the Doctor's (Peter Capaldi) frenemy will concoct such atrocities in season 9 that even Gomez was shocked by her character's actions.

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"Even I was a bit shocked at her level of disdain this year," Gomez told the Daily Record. "She has no boundaries that girl, she is very naughty."

The Mistress is expected to appear in the two-part premiere, which will consist of "The Magician's Apprentice" and "The Witch's Familiar." Both episodes will be penned by showrunner Steven Moffat.

Doctor Who follows the adventures of the Time Lord known as the Doctor. Currently in his Twelfth regeneration, the Doctor will continue to travel with Clara (Jenna Louise Coleman) as season 9 opens.

Find out more when Doctor Who returns to the BBC and BBC America this fall. Click the video below to get a glimpse of Missy at work in season 8.

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