«Have I already told you that I really, really hate temporal mechanics?»
«Once or twice before, yes,» observed wryly Kate Stewart, head of UNIT and daughter of the late Brigadier Alistair Gordon Lethbridge-Stewart, old friend of the alien known as the Doctor. The woman with whom Kate was talking, with short hair and piercing eyes, wasn’t the strangest thing with whom the scientist had had to deal with over the years. Even considering the fact that she came from the future, the 24th century, and was wearing strange clothes.

«How did you end up here, by the way?» Here was UNIT HQ in London, set in a different district than the last one, which included the Tower of London; it seemed better to separate the Black Archive from other sensible properties of UNIT, so Kate Stewart and her staff had decided to spread the offices all over the city, also creating different focal points for possible defence against alien and non-alien aggressions.
«That’s a good question, but I’m afraid I really can’t answer that, even if I knew how to explain it to myself.»
Eva Ferrari, a Lieutenant serving aboard the U.S.S. Europa (NCC-1648-E) as conn officer, wasn’t even remotely sure how she ended up in the 21st century Earth in the first place, let alone explaining it. Apart from her combadge, a hand phaser and a tricorder, she was left to her own devices in trying to return to her timeline, without disrupting it and changing the future.

«Why? It isn’t that we’re out of our depth in dealing with aliens or creatures from the future.» That was a younger woman, in between Stewart and Ferrari, with a white lab coat, a really long scarf around her neck and a really peculiar outfit.
«You see,» said Ferrari, looking at Osgood, «in my time we have rules about time travel. One of them, the most important, is the Temporal Prime Directive. By which, I must abide by not interfering with historical events and I am required to maintain the timeline and prevent history from being altered in any way. So, you see… I really can’t tell you anything.»

«But how can we help you…?»
«You won’t,» shrugged Ferrari. She didn’t seem particularly concerned by the prospect of being stranded in another time, less advanced than her own, with near to zero possibilities to actually return back and never see her friends, family and all forever.
«I’ll find a way to return back, one way or another. If I don’t, I won’t interfere with the proper unfolding of history,» she added, with a smile that didn’t reach her eyes, «and I’ll remain hidden, living a life as normal as I could. Because this will be the right thing to do. The only thing to do.»
«Even if you hate… temporal mechanics, whatever that thing is?»
«Especially for that reason, madam,» answered Ferrari, looking up to Kate Stewart from the tablet she was holding in her hands. Osgood's eyes widened at the answer, while both her and UNIT commander in chief looked with renewed respect at the Starfleet officer in front of them.

«I suppose that things go differently here, judging by your faces,» observed Ferrari, while looking back at the data stream she had engineered on the device in her hands.
«You won’t say,» answered Kate Stewart, «but we manage.»
«I know you do. The fact that you weren’t surprised at all in seeing me out of the blue and that you believe my coming from the future speaks volume.»
«Yes, well,» Osgood seemed a little uncomfortable, «that’s more complex than you may think.»
«Trust me, I really don’t want to know. And I’m fairly certain I know a bit or two about paradoxes, time travel and, well… temporal mechanics. Remember? If in my future, in your past, we’re going to meet or we’ve met… well, that’s a thing I prefer to live if and when it’ll happen. You’ve already told me, with a simple hint, that I’m going to return to my time frame. Do not interfere further.»

A knock knock to the door interrupted the three of them and one of the soldiers who had been escorting Ferrari through UNIT HQ entered, after being given permission from Kate: «They’re here, madam.»
«Thank you,» Stewart dismissed the soldier, before gesturing towards both Osgood and Ferrari to follow her.
«I must advise you,» she told the latter, «she doesn’t like soldiers or the military in general.»
«I don’t blame her, to be honest.» The blunt answer offered by Ferrari took both Kate and Osgood a little off guard, since Ferrari herself was, strictly speaking, in a military organisation, but no one dared saying anything more, since they finally joined the unnamed guests.

A blond woman, wearing a sky blue coat, a vibrant rainbow-striped shirt of an intense blue, high-waisted petrol blue trousers, gold suspenders, brown boots and rainbows socks was talking with another woman, of Pakistani descent, with her long dark hairs in a thick braid. The closeness of their bodies and their body language spoke volumes about them and their relationship, although the two of them didn’t seem aware of it or tried to ignore it,
«Doctor, you’ve come,» said Kate Stewart, while Osgood and Ferrari remained in the background.
The two women stopped talking and took a couple of steps away from each other, though they remained close, and the blond one took the lead, in almost a frantic way: «You called and talked about an old friend?»
Behind the two of them, a man with grey hairs and a perpetual smile on his lips, joined the one called Doctor and the other woman, quietly joining the conversation.

The Doctor looked past Kate Stewart, sweeping between Petronella Osgood and Eva Ferrari, before stopping dead at the sight of the latter. Her eyes widened in surprise and amazement: «What are you doing here?»
«So, it’s true,» Ferrari said, with a smile, «we know each other.»
The Doctor walked towards her, studying her: «Not yet, I dare say. Not for you, at least. Your eyes,» she explained, «your face. You are much younger than I remember. I…»
«… can’t talk about it,» Ferrari finished for her, nodding, «I understand perfectly. It could change the timeline as much as accidentally kill a butterfly.»
«Yeah, that too, in fact,» acknowledged the Doctor, with a smile. The Time Lady seemed very happy to see her and Ferrari really didn’t know why, apart from what she had grasped while listening to Osgood or Kate Stewart. The alien was energic, almost frantic in her talking, pacing and gesticulating with her hands, while her two companions (Yaz and Dan, respectively) were much more quiet and reserved. Especially Yaz, although she was always following the Doctor with her eyes, even when Dan started talking to her.

After a while, and a little rumbling from the Doctor, Kate was finally able to ask the Doctor the favour that had led UNIT commander in chief contacting the Gallifreyan: taking back to her own time stream the Starfleet officer. The Doctor did not let it be repeated twice and gladly accepted to do so, weaving to both her two friends and Ferrari to follow her, without even looking back to check if the others effectively were going to do so.
Yaz was the first to walk, matching the strides of the Doctor, while Dan remained back, walking alongside Ferrari, who was a bit perplexed by the person who claimed to know her pretty well, even if she was another man.

«Pretty confusing, isn’t it?»
«Indeed,» came the polite answer from Ferrari, «but I’m pretty sure, sooner or later, I will understand. I only need to wait for the right time, hoping not to screw up in the meantime.»
«Oh, I’m sure you won’t,» the Doctor replied, while they finally neared a big, blue police box, casually parked in plain sight, for everyone to see. But no one seemed to care: every pedestrian who was passing by, seemed oblivious of its presence, as if the blue box wasn’t really there.
Only then Ferrari, deeply lost in thought and in the few words she had exchanged with Dan, really noticed that she had followed the three of them outside UNIT HQ and into the morning crowd of people that she hadn’t noticed before.

«Here, come,» added the Doctor, while pushing one of the double doors and entering, immediately followed by Yaz. Dan remained outside, with Ferrari, who were looking at the blue box with a look of disbelief: «She’s expecting that all of us can fit in it, isn't she?»
«Well, yeah,» Dan smiled, «there will be a lot of space, trust me.»
«It’s a police box,» Ferrari pointed out, «from 1960s England…»
«It’s more than that. Come,» urged the other human, gesturing and preceding her into the blue box, «come and see.»

After a couple of seconds, Ferrari followed, entering for the first time into the TARDIS, that hummed a welcoming greeting to the Starfleet Officer; for her part, the woman looked around with amazement, never expecting what she was seeing.
Looking briefly towards the Doctor and her two companions, who looked back expectantly, Eva made a 360° round trying to take all in, before exclaiming: «Bigger on the inside, huh?»
«Dimensional engineering,» explained, with a smirk, Yaz.
«I didn’t think it was even possible to engineer dimensions,» although Ferrari was accustomed to the holodecks from her time, this was something completely different and, somehow, unexpected. It felt so real, somehow, that she thought she need to pinch herself to be sure she was awake.
«Maybe you can’t!» The Doctor’s smile was childish and beautiful and her answer wasn’t at all bitter, more a joke. «Welcome to my TARDIS, by the way. She’s pleased to get you a lift home!»

While Ferrari took a look around, followed closely by Dan, who was happy to chat with her, the Doctor and Yaz neared the console and started touching some buttons and levers: «24th century, we’re coming!»