Disclaimer: All recognizable characters and other Harry Potter elements belong to the wonderful J.K. Rowling. I own nothing but the plot.
It was dark outside. Too dark. Definitely not natural. The nearly full moon was shrouded in thick, grey clouds. The light could barely push through them, making it seem as if there was no moon at all.
She had on a long, black cloak. The hood was pulled up over her head, and the cloth flowed behind her, on the cobblestone ground of the walk. Before the Darkness, it would have been dangerous to be travelling down Knockturn Alley, alone, in the dead of night. Now, Knockturn Alley had been abandoned, like Diagon Alley, and all Diagon Alley's other offshoots.
The long cloak and hood probably weren't even necessary, but she could never be too careful. The Death Eaters were after her, and her little band of rebels. She hurried along the path, her long legs smoothly carrying her quickly to her destination. She delved deeper and deeper into the alley, and suddenly turned onto a side path.
It was nearly invisible in the night, and it would have gone unnoticed if any bystander had journeyed past. It was by pure chance that Neville had found this road, when he and Seamus were running from a group of Death Eaters who had found them loitering in the Alley.
They were there listening for any information on the whereabouts of either Voldemort's prisoners or his headquarters. Seamus had slipped on some 'slime of questionable origins' (as Neville had put it), and his hood had slipped.
It was more common to see a hooded, cloaked figure now, rather than with an uncovered head. Seamus was immediately noticed by one of the Death Eater patrol groups prowling about the Alley. One of them saw his face and recognized him as one of the insurgents from the rebellion.
Neville had pulled Seamus up, and they had run like Snakeface himself was behind them. They took as many twists and turns as they could, but somehow they couldn't lose them.
They somehow found themselves back in one of the more populated areas of the Alley, and were slowed down by the jostling of the bodies around them. One particularly nasty lady had shoved both of them to the side, and suddenly they had found themselves in a new Alley, with just a grey brick wall behind them- and no Death Eaters. That was the big thing.
They holed up there for a few hours, and none of their followers found them. They spent another few hours exploring the area, and found that it lead to a dead end, with a building at the back. The building was oddly reminiscent of Grimmauld Place.
They had come back to the campsite with the rest of the small band of fighters, and told them about the discovery. Seamus and Neville had led Hermione, Remus, and Charlie there to investigate the area further.
After a few days of exploring and putting up extensive warding, all of them had deemed the alley and and building safe. They moved everyone they had to the alley, and they had set up shop.
That had been three months ago. Now, Hermione was back in the new alley, which they had jokingly named [INSERT WITTY NAME HERE]. She had just come back from dealing with a Black Market apothecary dealer to get some more ingredients for her potions, as well as Professor Snape's (Severus'?) and Draco's. They were the only three who could brew well enough to trust, other than the Weasley Twins. Those two were more often helping out in developing new offensive, defensive, and healing spells, but they dropped by the Potions lab every once in a while.