Mags travelled to the planet Segonax with Captain Cook, an egotistical intergalactic explorer. Cook related that he had saved Mags when she was about to get shot with a silver bullet. Apparently, Cook wanted to somehow sell her to the Psychic Circus which had stopped on Segonax at the time.
The Seventh Doctor and Ace befriended her while looking into the Circus. Mags was later revealed to be a werewolf, her transformation triggered by moonlight. Mags seemed to revile and fear her transformations, and also feared the image of the moon itself. Cook managed to trigger her metamorphosis using artificial moonlight recreated by circus lights in an attempt to kill the Doctor for the amusement of the Gods of Ragnarok. The Doctor convinced her that she could control her feral instincts, but not before Mags ended up killing Cook himself.
After the Doctor had defeated the Gods of Ragnarok, she decided to stay behind on Segonax with Kingpin to re-start the Psychic Circus, despite her fears that her transformations might once again get out of control. (TV: The Greatest Show in the Galaxy)
Mags brought the circus to the Moon of Domusalba, which orbited her homeworld Vulpana, for its millionth performance. There she encountered her sister Adele, and her childhood sweetheart, Loz. Loz was leading a werewolf rights campaign as the President Of Vulpana was putting Werewolves in camps and forcing them to wear armbands in order to mark them out. Some refugees escaped to Domusalba, but then Vulpanian forces followed them.
The Doctor and Ace arrived Of Domusalba and assisted Mags in defeating President Carde, using a perfume that drove the people of Domusalba to rebellion. Ultimately Carde was killed by a werewolf and those oppressed by him were freed.