"I'm the Doctor...run for your life!" 

Nine (Christopher Eccleston) uttered that phrase over a decade ago, but it's as true today as it was in 2005. Doctor Who's companions need to be fleet on their feet, a lesson Pearl Mackie's Bill will learn in her debut episode.

Filming for the season 10 premiere began in earnest last week, and Cardiff natives took to the streets to catch a few snaps of Twelve (Peter Capaldi) and his new companion as they shot some of their first scenes together.

Scenes took place at Cathays Park (doubling for St. Luke's University Bristol) as well as two other locales, each of which saw Bill break into a jog at least once. Check out a few photos below!

Despite the chill of a snowy morning shoot, Mackie's character will ditch her winter duds as she sprints for the TARDIS.

Photos on Flickr show the actress pausing before walking through the familiar blue and white façade of the Doctor’s ship, her eyes trained on the sky. Will the premiere threat rain from the skies? Is more snow in the forecast? Only time will tell. 

Bill was also seen making tracks during a street scene, this time wearing the black and white checked shirt from recent Doctor Who promo photos (see image here).

What fresh danger will await the Time Lord and his new acquaintance in the season 10 premiere? Fans will have to wait until early 2017 to find out!

Doctor Who will return on Dec. 25 for the annual Christmas special (sans Mackie). Click the video below to see the season 10 stars in action.