Any sufficiently advanced technology is indistinguishable from magic.

- Arthur C. Clarke

'You're taking me home?' Martha questioned as she stepped out of the Tardis back onto familiar ground.

'I thought you might be missing…'

The Doctor stopped suddenly gazing up into the sky.

'What? What is it, what's wrong?' Martha's voice once again held an uncertain tone as she watched the Doctor carefully.

'Something's wrong…' He ran back inside the Tardis without further explanation and she followed him, watching while he pressed various buttons on the console.

'What is it? What's happened?' She tried to keep the frustration out of her voice now fully accustomed with the Doctors penchants for avoiding questions.

'No, no, no…this doesn't make any sense!' He ran around to the other side of the ship pressing more buttons. 'It can't be happening, this is impossible!'

'What?!' Martha threw her hands up in an effort to gain his attention.

He glanced at her briefly knowing any explanation he gave her she probably wouldn't understand but as he turned back to the computer he figured it couldn't hurt, saying it out loud might at least help him to understand.

'I'm picking up fluctuations in energy between parallel universes but no conduit between them and the rift.' His eyes scanned the numbers on the screen carefully. 'It doesn't make any sense…'

Martha threw him an indignant look. 'You're telling me.'

'Imagine every choice you've ever made, becoming a doctor, turning left on a street corner, saying no to a date...'

He turned fully aware he was babbling but she seemed to be following so he continued, 'Now imagine there is a you out there who took the other option every time… became a chef, turned right, said yes…'

She nodded mentally piecing everything together, 'So there's another me, in a parallel universe living my what if's?'

'And not just one!' He smiled broadly as he watched everything start to click.

'There's an infinite number of possibilities and an infinite number of worlds but opening the rift between them creates a paradox that would tear both universes apart.'

'That's not a good thing then?'

Had she blinked she would have missed the look of anguish that flashed across his face but it was quickly replaced by a large smile.

'The Tardis is showing me flares of quantum activity which means if I'm right someone here on earth is accessing an alternate universe without opening the rift!'

The Doctors enthusiasm was catching and Martha felt herself getting swept up by his excitement.

'So where do we find them then!?'

'We start…' He pressed a button that set of a tangent of beeping, '…by finding out where exactly the energy is fluctuating.'

'We can do that?' Martha stared amazed as a bunch of random numbers popped up on the screen in front of them.

'This beauty can do a whole lot more than that!' He watched the numbers multiply on the screen waiting impatiently for the answer, 'Come on…come on. Ah ha!….oh no…'

She found herself once again asking the question that was always on her lips, 'What? What is it?'

'Oh no no no no no, this is bad, very bad.' He hit a few more buttons hoping to change the outcome but the results stayed the same. 'It's coming from Torchwood.'

'What's Torchwood?'

'Hold on.' He said taking hold of a lever. 'You're about to find out.'

He pulled down and the Tardis shook violently before disappearing into thin air….

Jack stared at the glowing hand the feeling of anticipation building inside him. Any second now, any second he just knew it...

A loud buzzing filled his ears and a grin broke out across his face as the giant blue box materialized before him.

'I knew it! I knew you'd come back!' He jumped up excitedly waiting patiently as the door to the Tardis slowly creaked open.

He was slightly taken aback when a strange man stepped out. 'Hang on you're not…'

'Jack Harkness!' The Doctor's eyes went wide and he grinned as his gaze fell on the man standing before him. 'You old son of a gun!'

'Doctor…?' Although hesitant at first he knew instantly it was the Doctor by his response.

'No, the Doctor decided to quit, gave me this cool box though… any idea what it does?'

'Pretty useless, so I hear…'

There was a pregnant pause before they both finally laughed, Jack leaping forward and pulling the man into a hug, patting him firmly on the back.

'New look?'

'New teeth…not too sure about them?' The Doctor bit down a few times as they pulled apart wondering if he'd ever get used to them.

'So how in the blazes did you wind up here, on earth, working for Tourchwood.'

'Now that, that is a long story.' Jack's eyes fell upon the Tardis door as it opened and was surprised when he didn't see Rose stepping out.

'Now who is this beautiful lady?' He asked stretching out his hand, '…And where is the lovely Miss Tyler?'

A shadow passed briefly across the Doctor's face but he kept it well hidden.

'Jack meet Martha Jones, Martha meet Captain Jack Harkness.'

Jack brought her hand to his lips and she smiled not at all caught out by the action, 'You sure know where to find them Doctor.'

'And what is that supposed to mean?' Jack turned to the Doctor laughing, surprised by the sullen look the man was wearing. Then it hit him and his heart seemed to drop as the Doctor simply shook his head.

He didn't need to ask who he was referring to, Jack had only ever seen the Doctor in that much despair over one person. 'What happened?'

'She got trapped in an alternate universe…' The Doctor cleared his throat desperate not to choke up as he told the story, it was the first time he'd told anyone since it had happened. 'The rift closed and there was no way back to her.'

For reasons unbeknownst to the Doctor Jack's face broke out in a huge grin. 'Well you'll never guess what I just found!?'

The Doctor tried to squash the bubble of hope rising inside him, not wanting to go through the pain of being disappointed again but a small, small part of him couldn't help but feel excited. 'Without opening the rift… it's impossible.'

'Guess again Doctor!' Jack turned on his heel practically bouncing as he motioned for them to follow him.

'About a month ago we found the wreckage of a ship that crashed, looks like the captain was a scientist but he died instantly so we couldn't ask, found some pretty neat stuff though…'

He led them into one of the backrooms where a funny looking mirror stood propped up against the wall. 'Doctor I present to you the one and only quantum mirror in this universe.'

Martha followed the Doctor as he took a closer look at the shimmering surface. The thought of bringing home Rose Tyler sent a shiver of excitement through her but also caused her a small sense of dread.

She knew how much the Doctor missed her despite the fact he rarely mentioned it and nothing would please her more than to reunite them but it also left her wondering what would happen to her as the Doctor's current companion.

'What does it do then?' She asked turning back to the man who was still grinning like an idiot.

'It connects to mirrors in other universes using this…' He held up a small controller in his hand. 'Might not be one on Rose's earth but I'm willing to bet there's one somewhere out there in space and with the Tardis distance shouldn't be a problem.'

Martha frowned confused, 'But the Doctor said there was an infinite number of realities how are you supposed to find hers?'

The grin dropped off his face but appeared seconds later on the Doctor's as he turned around beaming.

'We hook it up to the Tardis! I used it to find Rose as the gap was closing… Jack you're brilliant!' He pressed his lips to the captains forehead before running out of the room to make the right calibrations.

Martha and Jack just shared an amused look before following after him.