‘The Greatest Show In The Galaxy’ introduces us to the character Mags. Captain Cook’s version of Ace she is a Doctor Who companion who never was.
Over the course of the 4 episodes we learn that she feels indebted to Captain Cook because he saved her life, something which allows her to put up with his boorish behaviour. It is very possible that she suffers an inferiority complex, due to her nature.
It is eventually revealed that Mag is a werewolf, undergoing a feral transformation from moon light, although artificial moon light and moon symbols would also appear to trigger it. The transformation takes the form of elongated teeth and a change to her eyes but it is possible that true moonlight could change her further.
It could be that everyone on Vulpana, the planet Mags originated from, has this ability (or curse). Perhaps they have learnt to cope with these changes and Captain Cook took her away before those lessons could be passed on to her. He could also have viewed the locals as savages and taken Mags to educate her.
Alternatively Mags might be unique, or at least in the minority. The locals might use silver bullets to control the infection. If every native on the planet is a werewolf then perhaps Captain Cook was on an hunting party for off-worlders and saw something promising in the girl.
Previously there has been indications that people of this time period can give themselves artificial gifts. If Mags is human could her werewolf nature be something that was implanted? This raises questions whether this is deliberate or an accident.
The fact that the transformation is triggered by artificial moonlight and symbols indicate that it could be due to mental suggestion rather than a biological process. If technology is behind the changes then it only needs the host to think they are seeing the moon.
The parallel with Ace is obvious, especially as this is very much Ace’s story arc. Both characters are young women with dangerous sides to them. A savage temper and capacity to harm that they don’t understand and fills them with fear about what they might do.
Compare Mag’s transformation with what occurs to Ace in ‘Survival’. The difference is that Ace found her animal instincts alluring. Her Mag’s dreads the inevitable change and the loss of control.
Both the Doctor and Captain Cook are prepared to exploit their companions. The Doctor would use Ace as a pawn, as in ‘The Curse of Fenric’, while Captain Cook is willing to use Mags to kill his enemies.
The biggest difference is that the Doctor constantly puts himself at risk to save Ace. In contrast Captain Cook doesn’t lift a finger to save Mags from a robot and is willing to send her to her death in the ring in his place.
Given his attitude to her we must ask why Captain Cook saved her life. It would seem that he was aware of what she was when he saved her life. Why did he feel it was safe to travel with someone who could turn into a werewolf, especially as we saw she always had the capability to kill him.
Did he at one point care for her? At some point Captain Cook may have been a kind man before becoming jaded or falling under the influence of the Gods of Ragnarok. He might have taken the risk of her company because he genuinely wanted to save her.
There is also plenty of evidence to suggest that Captain Cook was just using her. Always looking for a way to turn circumstances to his advantage he could have seen Mags as a secret weapon, that no one would suspect.
In his final scenes he attempts to give Mags orders. In the past he could have controlled Mags through sheer force of will. His talk of splitting the proceeds suggests that he has used her in the past to kill others for profit.
In which case Captain Cook isn’t an explorer but a thief. It might not have been difficult for him to use his reputation to gather travelling companions on expeditions to distant alien planets. All he had to do was wait until a full moon and loot the bodies once the werewolf Mags had her fill.
Adventures could be built around these early days, allowing PCs to witness the first meeting between Cook and Mags for themselves. They could even be targets for Captain Cook’s scam.
At the end of the story Mags stays with the circus to help them rebuild and learn to control her abilities. Might the Doctor have returned later to make her an official companion? This would lead to some interesting adventures with a particularly volatile companion.
The twist would be that whenever Mags is placed in danger she has the option of unleashing the beast within her. While that might save her in the short run what will the beast do before she awakens and can she live with the guilt?
An adventure could also focus on finding a cure for Mags or protecting her from would-be werewolf hunters. This would be a good opportunity to learn more about the nature of her condition.
If the condition is transmittable then PCs might become infected themselves. This could require a trip to Vulpana to find its point of origin. You may wish to tie this with the werewolf seen in ‘Tooth and Claw’, the Earth based werewolf race in the Big Finish audio ‘Loups-Garoux’ and the Jax from the 8th Doctor novel ‘Kursaal’.