‘This can’t be happening.’ There was an edge of hysteria to Thawn’s voice in the darkness, and while Sadek knew she was going to have to calm the young officer down, first she was going to have to slow her own racing heart, her own tense breathing. That was not very easy, when the only thing breaking the darkness around them were the faint rings of light of forcefield projectors in a long, gloomy row of cells in a brig far darker and danker than any Starfleet holding room.

They had been beamed directly aboard, plucked from the deck of the King Arthur aboard this shadow of Endeavour, this twisted mockery of their home – bigger, better armed, a weapon of war and death and suffering. Sadek could barely see into the cells from here, though knew from the silhouettes of the projectors’ glows that Cortez was beside her, and could just about make out the shape of Thawn in the cell opposite.

‘What is happening?’ Rhade’s voice came from the gloom beside Thawn, and he stepped forward for light to paint him in a bright outline.

‘Great question,’ said Cortez in an unusually flat voice. ‘We found out a year ago the Wild Hunt pirates were evil invaders from another reality. But they got beat and were killed or sucked into whatever vortex that station they were using to try to hop dimensions created. Now there’s another, evil Endeavour?’

‘Oh yeah.’ Sadek winced. ‘Matt never told any of you.’

‘Told us what?’ Thawn didn’t sound calmer.

‘The alternate dimension Halvard gave him a warning before he died: that there were more of them. Matt suspected that the Wild Hunt was just one small part of another unit. A much bigger unit.’

‘Like this big ship, run-down to all hell,’ continued Cortez with dawning horror, ‘that’s been hiding out in a wild-ass part of space like where the Neutral Zone butts up against the Talvath Cluster, and is commanded by Evil Leonidas MacCallister.’

‘Yeah,’ said Sadek. ‘Something like that.’

‘Wait.’ Rhade’s voice dropped ten degrees. ‘Where’s Lieutenant Dathan?’

Sadek took a quick step forward, peering through the rings of light in the darkness. ‘She’s not in there with you?’

There was a swish of doors opening, thudding footsteps of boots on metal, and with clicks of pinprick precision, light after light down the long corridor of the brig burst to light to herald the new arrivals. Sadek could only see the glow, and even as she tried to position herself to see, the figures were almost in front of the cells before they were clear to her.

‘Oh, hell, the universe has the silliest sense of humour,’ she sighed as she recognised, stood in the lead, someone who looked a lot like Matthew Rourke.

He was, of course, leaner, more muscular, clean-shaven, his hair only millimetres long. It was as if someone had taken all of Matt Rourke’s softness and scraped it off to sharpen each edge. He arched an eyebrow at her. ‘Either universe. You must be Doctor Sadek.’

‘Oh, hey,’ said Cortez, and pointed to the figure on Rourke’s right. ‘So must you. This won’t get confusing at all.’

‘God,’ sighed Doctor Sadek, looking at herself if she was much more skimpily dressed. ‘I already hate this.’

‘You should,’ said her counterpart in the low drawl she usually reserved for when patients were being particularly uncooperative. ‘You’re going to die in there.’

‘They’re subtle,’ said Cortez to Doctor Sadek out of the corner of her mouth. ‘Nobody said they were this subtle.’ If Thawn had sounded borderline hysterical from panic, she thought, Cortez sounded like being glib was the only thing keeping her from breaking down screaming.

‘My name,’ said the man who looked like their captain, ‘is Commander Thaddeus Rourke. You are all in the hands of the imperial starship Endeavour. And if you are cooperative, you may look forward to slavery rather than death.’

‘I always thought Matt’s middle name was pretentious,’ drawled Doctor Sadek, ‘and those are crappy choices. Not to mention the fact that you are in the middle of our universe, people will come looking for us, and after a year of trying to lay low you’ve just stirred a hornet’s nest.’

The other Sadek gave a whisper of a smile. ‘We won’t be here long enough for that to be a problem.’

But before Doctor Sadek could press that point, from the cell across there was a crackle of energy as Adamant Rhade smacked his palm into the forcefield. ‘Where’s Lieutenant Dathan?’

Thaddeus Rourke turned with an imperious gaze. Then he gave a smile that made Doctor Sadek’s back tense. ‘You mean Agent Dathan.’

Footsteps rung out at his gesture back down the corridor, and Sadek heard Cortez swearing up a storm in Spanish under her breath as, in the same crisp military uniform as the rest of them, Dathan Tahla approached with an expression so utterly neutral it could only have been perfectly cultivated.

Rhade stared at her, then at Rourke. ‘There are duplicates,’ he hissed after a heartbeat. ‘This is your Dathan, where’s ours -’

‘Dead,’ said Dathan Tahla in a flat voice. ‘Abducted by us upon arrival and replaced by me, who insinuated myself into the office of Admiral Beckett, who made the most of being placed aboard Endeavour.’ Her chin tilted up an inch. ‘If you doubt me, then how could I possibly know that for about five minutes after the Century Storm, you and Thawn were not to marry, only for her to get cold feet? You told me this.’

Rhade took a stumbling step back, white as a ghost, and Doctor Sadek leaned to the forcefield in a desperate effort to recover control. ‘What do you mean, you won’t be here long?’ she said, eyes locking on Rourke and her counterpart.

‘We’re going back,’ said Rourke simply. ‘You were very unlucky. We are on the verge of finalising our recalibrations of our warp drive to allow us to return to our universe. We detected your ship in the vicinity and knew we couldn’t risk you stumbling upon us and sending word. Be grateful we didn’t kill you.’

‘Or don’t be,’ murmured alternate Aisha Sadek. ‘Our experiments in studying the quantum frequency in bodies to perfect our calibrations of moving between universes… continue. You will all be of most excellent use.’ She glanced towards Rhade and Thawn’s cell. ‘Especially the xenos.’

Before Doctor Sadek could say anything to try to draw back attention, Commander Rourke slid an arm across her counterpart’s back, his voice dropping. ‘Make sure you play nicely with the toys, my dear. We might need them.’

The other Aisha Sadek ran her fingers along his arm. ‘There’s plenty spare,’ she purred, leaning in for their lips to be mere breaths apart.

‘Gross,’ said Cortez and Sadek in unison before they could stop themselves.

Thawn was watching Dathan, though, dark eyes beady against her pale skin. ‘You’ve been lying to us,’ she said in a low voice, ‘all this time. I can practically smell the guilt. Why didn’t I notice it before now?’

‘Your senses must not be very good,’ was Dathan’s flat response. ‘You couldn’t tell before that I was lying, and I feel absolutely no guilt now. I am a servant of the Empire, and I have finished my mission.’

‘Not,’ said Rourke in an arch voice as he turned to her, ‘without missteps. But we can worry about that later.’

Doctor Sadek clenched her fists. ‘What happens next?’

‘Experiments!’ said her counterpart in a cheery voice. ‘Xenos first. Do you have any suggestions, my dear?’ Her eyes turned on Dathan. ‘The bolshy one or the one who really hates you?’

Doctor Sadek didn’t know if she imagined a hesitation because she wanted to see it, wanted to believe that someone who had worked alongside them for a year now was not simply a spy and a snake. But any of that hope died as Dathan turned to the cell of Thawn and Rhade and gave an imperious gesture, expression still flat. ‘Her.’

‘Good,’ purred the other Sadek, and as she spoke another figure came thumping down the corridor in fully body-armour, a phaser rifle slung over their shoulder.

If Thawn had looked pale before, now she looked ghostly, her eyes as big as dinnerplates. ‘Oh, no,’ she breathed. ‘No, please…’

Sadek swallowed bile. She had never met Noah Pierce, dead in the battle that had brought her and Cortez to Endeavour over a year ago. But she’d seen the files, and knew he and Thawn had been close; knew his death had hung over her throughout their pursuit of the Wild Hunt. Now his counterpart was advancing on the cell she was trapped in, just as much sharp edges as Thaddeus Rourke.

Rhade side-stepped in front of her. ‘If you need someone for experiments, I’m right -’

But the forcefield came down, and Pierce’s stun baton lashed out, thudding into Rhade’s gut with a crackle of energy.

‘Right here.’ Pierce’s voice was like granite. ‘I know, scum. You’re next.’

‘Rourke.’ Doctor Sadek was as close to the forcefield as she dared. ‘If we’re missing too long, Endeavour will come looking -’

‘If I let you go, your ship will come looking,’ Thaddeus Rourke rumbled. ‘I rather hope they do. Then finally you can taste the might of the Empire.’ Beyond him, Pierce grabbed a struggling Thawn, dragging her out of the cell and reactivating the forcefield as Rhade writhed on the deck. Rourke looked at his Sadek. ‘Is that all you need, my dear?’

Her eyes swept over the prisoners. ‘For now.’

‘Then you and I,’ said Rourke, turning on an expressionless Dathan, ‘are due a debriefing.’

‘Dathan,’ croaked Rhade, by now on his knees. ‘We trusted you…’

Rourke, his Sadek, Pierce, and the struggling Thawn were moving away from the cells, but Dathan Tahla lingered a heartbeat more, looking over her shoulder at him as if he was nothing more than a stain on her boot. ‘That,’ she said quietly, ‘was your mistake.’