Martha was about to head out on her latest mission, when something stopped her dead in her tracks. Her phone was ringing. But it wasn't the usual ring tone. It was the special one. The one she reserved for just one person only.

The sound of the TARDIS blared out from her phone, signalling that her assistance was needed. She hadn't heard that noise in 10 years. What a decade it had been.

She snatched up her phone, and immediately answered.

'Doctor?'

'Erm… no… my name is Yaz.' Who was Yaz? If it wasn't The Doctor, then she must be a companion. Especially if she had her phone. It only stayed on the TARDIS. Martha was anxious, and needed to know what was going on.

'Where's the Doctor?'

'That's what I was hoping you could help me with.' Yaz paused. 'I need to ask you something first.'

'What?' Martha was getting more anxious by the moment.

'Are you Martha Jones?'

'Yes, I am. Well, Martha Smith-Jones, but yes, that's me. What's going on?' The girl, Yaz, sounded nervous on the other end of the phone. She sounded young, Martha noted.

'The Doctor has been taken. I reckon by an alien force but there's no trace. The TARDIS gave me this phone and you're the only contact in it. So I figured, you might be able to help?' Her tone was pleading. The poor girl was clearly scared, but trying to be brave. Martha certainly knew that feeling.

'You're friends with The Doctor?'

'Yeah, three of us travel with The Doctor. We're all looking but we don't have alien expertise. I'm a police officer so I have some training, but I'm really out of my depth here. Is there anything you can do to help?'

Martha took in the whirlwind of information. She didn't think it was a trap. Her phone hadn't rung from that number in 10 years, so it would seem a bit futile if an enemy wanted to get to her. Surely there would be other people who would be first in the firing line? Still, she had to test Yaz, just in case.

'I need you to answer some questions about The Doctor first.' She said calmly. Yaz wanted to object, but she knew the stakes were high, and Martha quite rightly would need verification.

'Okay, go for it.'

'What species is The Doctor?'

'Time Lord,' Yaz answered immediately.

'Who is The Doctor's worst enemy?'

'The Daleks.'

'And why is that?'

Yaz faltered for a moment, trying to think of the reason. There were many.

'There's a lot of reasons. Firstly, the time war, when The Doctor's whole planet was destroyed by them. But then Gallifrey returned safe, and the Daleks keep taking people away from The Doctor. The latest run-in with them was not fun.'

Martha's mouth dropped in shock. There was a lot to unpack there. She started with the most shocking revelation.

'Gallifrey is back?'

'Yeah, although we haven't been yet. The Doctor keeps putting it off.'

Wow, things really had moved on! When she found The Doctor they would have a lot of catching up to do.

'From the sounds of it, you've met the Daleks then?'

'Yep. Still gives me nightmares.'

Martha felt a chill run down her spine. She was silent for a moment.

'Yeah. Me too.' She replied softly.

Yaz was clearly safe. Martha was glad her old friend had found more people to travel with. He needed that. But the fact that he was missing, and his new companions were at a loss at what to do, was not good. No wonder Yaz was worried.

'Have I answered all your questions?' Yaz asked anxiously, clearly aware of the ticking clock.

'Yes, yes you have. Of course I'll help you.' She heard Yaz jump up in excitement.

'Oh my god, yes! Thank you Martha, thank you!'

'Don't thank me just yet, we haven't found The Doctor yet. Now, we need to come up with a plan.'

'What resources do you have?' Yaz asked. Martha smiled. Yaz asked all the right questions. Martha knew they were going to get on like a house on fire.

'I'm a freelance agent. I dabble with UNIT and Torchwood, so I have a few contacts who will be more than willing to help us.'

'I thought UNIT didn't exist anymore? And what's Torchwood?' Martha's enthusiasm deflated a bit. She was dealing with newbies then. Still, no matter. Nothing like a baptism of fire.

'It's all been pushed underground. We work in secret, to protect the human race. They've got all sorts of technology that could help us with tracking.'

'That's great! How can we use it?' Yaz asked, excited.

'Well, you can't use it… but I can. Give me a day to sort some stuff out, and I can come to you. Where are you based?'

'A day? But The Doctor needs us now!' Martha's heart broke a little at the desperation in the young woman's voice. Oh, how she knew that desperation. She stayed silent for a moment, thinking through her answer, before making a snap decision.

'Okay, okay, you're right. I'll come straight to you, and get my husband to follow up with the tracking equipment.'

'Yeah, do that! We're in Sheffield. I can text you the address.' Sheffield. Martha could make it there in a couple of hours if she stepped on it.

'Okay Yaz, sit tight. I'll be with you in a couple of hours.'

'What can I do in the meantime?' Yaz asked, still at a loss. She didn't want to wait around and waste precious time.

'Have you called the police?'

'Well… I sort of am the police. But I asked my colleagues to come help…'

'Talk me through what happened,' Martha asked kindly but firmly.

'Isn't it better to explain when you're here? I don't want to waste time…'

'Don't worry, I can talk and drive at the same time. The wonders of Bluetooth.' As she was talking to Yaz, she was already contacting her parents to come look after her son. She cancelled her current mission and delegated it to her second-in-command. Yaz seemed appeased by this, and continued talking.

'Well, I last saw The Doctor this morning. I'd gone to sleep, then came back to the TARDIS and nothing. Not totally unusual for The Doctor. But after searching everywhere, there was no sign. I called. No response. Something just felt off. Then I left the TARDIS and found…'

Martha encouraged her to continue, realising that this might be traumatic for Yaz.

'Go ahead Yaz, in your own time.'

'I found a pool of blood. Right where The Doctor and I had last talked. Except there was no trail of blood leading away from the scene, so my first thought was…'

'He's been teleported somewhere else.' Martha finished for her.

'She.' Yaz corrected her. Martha blinked in surprise, just as she was grabbing her bag to pack with clothes.

'I'm sorry?'

'She. The Doctor is female now.' Martha felt a small grin grow.

'Really?' She asked in surprise. Maybe she shouldn't be so surprised. She knew regeneration could create a whole new man, so what was the difference between that and changing genders? Besides, gender was probably defined differently in Time Lord Culture. She finished shoving clothes into her bag, grabbed her car keys and exited the front door.

'Damn, The Doctor is full of surprises. Jack would have a field day.'

'Oh, he did,' Yaz joked with her. Despite the emergency, it was nice to get to know more about The Doctor's new companion.

'You know about Jack?'

'Well, we only met him briefly. Tall, American, good looking…'

'That's Jack,' Martha smiled wistfully. Oh, how she missed her immortal friend. Maybe she should use the tracking software to find him too… or maybe just stick to one problem at a time. 'Yaz, I'm just getting in the car, so keep talking to me.' She turned on the ignition, and her call suddenly blared out into the whole car. Hands free joys.

'What should I do next?' Yaz asked, now coming to think of Martha as a kind of mentor. Martha chewed her lip in thought, thinking of a plan.

'You said the police are there?'

'Yeah, taking forensics. I thought it would be useful.'

'It will be yeah…' Martha paused, a horrible realisation suddenly dawning on her. 'Wait a minute, you said there was blood. You're presuming that it's The Doctor's?'

'Yeah?'

Martha felt panic run through her. In her desperation to help, Yaz had made a terrible mistake.

'Yaz, the blood! If it gets tested, they're going to find out The Doctor isn't human!'

Yaz was silent for a moment, her mistake catching up with her. If The Doctor was uncovered as an alien, who knew what the repercussions could be!

'But, how else are we going to be able to trace her? I know it's risky, but surely having all the evidence will make it easier to find her?'

Martha stayed silent for a few moments. Yes, it was an issue. The forensics teams wouldn't know what to make of it. She might be able to play it off as an inconclusive result.

'Okay, I have a possible solution for that. I can pull a few strings and should be able to get myself into their lab, to try and mislead the evidence. But one thing at a time, I need to get to you first.'

'I'm sorry,' Yaz said, sounding so dejected. Martha could sense the shame in the young companion's voice, and tried to reassure her.

'Hey, its okay, Yaz. It's not the worst thing to happen. We can fix this together. We'll get The Doctor back.' She thought she could hear a sniff down the end of the phone. To distract her new friend, Martha started a new line of questioning. A softer, gentler one.

'So, how long have you been travelling with The Doctor?'

'Erm…about two years I think? Wow, it's gone so fast!' Martha could already hear the excitement pick up in Yaz's voice.

'Yeah, it does go by so fast. Yet, so much changes.' Martha knew she sounded wistful, but she couldn't help herself. She loved The Doctor, but he had changed her life. Irreparably. It was both a blessing and a curse. She wasn't sure if Yaz caught that in her voice, but she didn't press too much.

'When did you travel with her?' Yaz asked, clearly very interested to find out more about a previous companion.

'About, ooh, 13 years ago now? Wow, now that's gone fast!' Yaz laughed in response. Martha was pleased she was able to take her mind off everything.

'Which face did you travel with?' Yaz asked, curious.

'My Doctor, when he was a man – sorry, she – was tall. Pretty tall. The Doctor wore a long brown coat, a suit with converse, and a long trench coat. I mean, trench coats were in back in the late 00's, but it was a look.'

'Oh, that face was the really attractive one?' Yaz asked impulsively, before realising what she'd said. Martha could feel herself blush, because she knew exactly what Yaz had implied. That was all ancient history for her, and she couldn't be happier with Mickey, but still… The Doctor was attractive. There was no denying it.

'Don't let your Doctor know that. She'll get a complex!'

'Oh, she's already got a complex,' Yaz joked. Martha could sense there was more to Yaz's friendship with The Doctor than she had initially thought. Those questions could come later.

'So, what does your Doctor look like?'

'She runs around in a long, blue coat. She wears suspenders, tends to wear rainbow t-shirts.'

'The coats never change,' Martha joked.

'What else can I tell you? She's slim, blonde…'

'Of course she's blonde,' Martha muttered. The Martha of old would have been bitter, as it harked back to her days of being the rebound companion, but since meeting Rose, and Mickey, that whole ship had sailed. And she was glad of it.

'What was that?' Yaz asked.

'Oh, nothing.' Martha lied. Yaz didn't need to hear about Rose right now. The poor girl didn't need the exes to be brought up during this emergency. 'What's her personality like?'

'She's so optimistic. Like, all the time. Full of beans. Doesn't stop talking. Manic. Brilliant. She's the best person I've ever met.' Yaz paused. 'But, she does have her moments of sadness. Sometimes when she thinks I can't see.'

'That's The Doctor,' Martha confirmed.

'What was she like with you? Does personality change with regeneration?'

'I think it does. But to be honest, your Doctor sounds so similar to mine. Manic. Brilliant. Except, I feel like my Doctor could be dark, sometimes. The rage of a Time Lord is not something you mess with.' She paused, realising how deep they were getting.

'Yeah, it's not fun to witness.' Yaz admitted. The anger had never been aimed at her, but she had seen it directed at enemies. She'd seen flashes of it the night before, when she'd stumbled on her confrontation with Danny. Interesting that it wasn't just her Doctor.

'Yaz, how old is your Doctor?' Martha asked, curious to know how long it had been for her friend.

'She says she's lost count. But, she told me once that she was over 2000 years old.'

Martha's hands tightened on the wheel. The Doctor hadn't seen her in over 1000 years? How would The Doctor even remember her? She suddenly felt cold, a feeling of dejection washing over her. It wouldn't stop her new mission, but suddenly she felt less excited about a reunion.

'The last time I saw The Doctor, he – sorry, she, I will get the hang of it – was only 900 years old.'

There was a pause, as silence suddenly befell the phone call. She could tell Yaz was trying to think of something to say. What she said surprised her.

'I've heard your name before,' Yaz offered.

'Really?'

'Yeah. We were at a fancy dinner and this journalist came out of nowhere…'

'Caroline?'

'Yes it was! And she mentioned you. It wasn't a long conversation, but when Caroline said your name… The Doctor reacted.' Yaz paused, and Martha waited with baited breath. 'The Doctor had this look of nostalgia, and sadness, all over her face. Seems to me, that she remembers you. Well.'

Martha let out the sigh of relief she'd been holding. That's just what she'd needed to hear.

'That's good. Because when we find her, The Doctor is going to get a mouthful. Or a long hug. I haven't decided yet.' She heard Yaz laugh down the phone. Martha continued to drive, weaving in and out of cars on the motorway. She would be in Sheffield soon.

Ready to meet The Doctor's new friends.