They came at midnight.

What started out a low rumble from beyond the horizon soon turned to screams and explosions and flashing lights. Mundane men in military uniforms pored into the city, marching down the streets in perfect formation and as the local people scattered in all directions, some hauling sacks of food and belongings, some clinging onto their children and crying out for mercy. No one knew where they came from, but what they wanted was clear enough. They wanted the city. They wanted Warsaw.

"We have to do something." Rivvy said again, gazing across the dark library from her perch at the high, stained-glass window. Her grandfather stood with his back to her, leaning against a broad oak desk with his shoulders hunched. Even in his old age he was an imposing man, broad and tall with a thick mane of silver hair and beard bushy enough to conceal most of his tan, weather-worn face.

"You know we can't." Steven, Rivvy's tutor and her grandfather's advisor, replied softly from another dark corner of the library. They'd blow out all the candles and gas lamps when the first of the mundane troops reached the city. There was no way for them to even see, let alone enter the institute, Rivvy knew- but an invasion of this scale, even a mundane one, had put her grandfather on edge enough to call the entire conclave to institute to hole up and weather the attack.

"But we're shadowhunters." Rivvy said angrily, her voice rising above the hush in the library enough to make her grandfather wince, she noticed with satisfaction. "Helping mundanes is what we do."

Steven took a slight step forward so that the silvery light from the window fell across his face, the occasional flash of gunfire or explosion from the streets below lighting him up enough for Rivvy to see he was wringing his hands. Curious.

"We do not interfere with mundane politics and affairs." He said calmly, his slow, easy tone not matching the tension in his body. His lips were pressed into thin line, the wrinkles in his forehead deepening as he furrowed his brows in a way that left Rivvy wondering if maybe- just maybe- she might get to him yet.

"So we sit back and let them kill each other?" She demanded, eyes flickering to her grandfather, who hadn't moved to turn around in what seemed like hours.

Steven sighed and ran a hand through his hair, dark and streaked with grey. "Until they threaten the nephilim or any downworlders, yes. We leave them to fight their own wars, as we always have."

Rivvy shot the back of her grandfather's head a look of pure steel. "Fine." She spat, fingernails biting into her palms as she pushed herself off the windowsill. "We'll just hide in here while innocent people die."

As if the invisible chord holding him back had snapped, her grandfather whorled, his dark blue Lightwood eyes flashing with a burst of anger. Anger, Rivvy realised, that was directed at her.

Her grandfather had never hit Rivvy or her brother since they came to live with him in Warsaw at the beginning of the summer, not like other guardians often did, but she had been at the receiving end of his rage more than a few times, and she knew it was only a matter of time before he resorted to other forms of discipline. As he straightened to reach his full, imposing height, Rivvy saw him not as the quiet grandfather who had taken her in after her mother's death, but as the well respected head of the Warsaw institute. Suddenly, she understood why the conclave seemed to tip toe around him so carefully.

He opened his mouth to speak, shout, something, and there was thunder in his eyes, but just as Rivvy was shrinking away the library doors clanged open and three shadowhunters charged in. One of them Rivvy knew by name- Henry Cartwell was an emissary from the clave who had arrived a few weeks ago, but the other two members of the conclave rarely visited the institute, and Rivvy had never spoken to them.

Henry was the first to reach her grandfather, where he bent with his hand on his knees, panting as if he'd run all the way from the suburbs.

"What is it, Cartwell?" Rivvy's grandfather demanded, all traces of his annoyance towards Rivvy replaced with a cool, profession tone of authority. "Out with it, man."

"The mundane army." Henry panted, and when he straightened, his face was twisted into an expression of shock and fear. "There's more coming, behind them, from the Southeast."

"You know very well there is nothing we can do under clave law, Cartwell." Her grandfather grumbled, some of his straight posture giving way to a slight hunch of defeat. "The mundanes can either fend for themselves, or-"

"Not mundanes." Henry said cooly, an edge to his voice that sent a sudden chill through Rivvy, still watching from the safety if the window. "Demons."

The room went cold, as if all the heat from the fire had been leeched out by the very mention of the word, as if everyone simultaneously sucked in their breath and held it. The silence was palpable, collecting in the air and sticking to Rivvy's skin like moisture on a humid day, making her tongue thick and her head fuzzy.

"Demons?" Her grandfather repeated after what seemed like an age.

Henry Cartwell nodded, and the two members of the conclave behind him stepped forward, witnesses to his testament.

"An army of them."

The front hall of the institute was a sea of noise and tension. The entire conclave was gathered below the first floor landing, almost all dressed in gear, huddled in groups to speak in hushed voices, as if whispering about the oncoming threat was enough to put it off. There was no fear in their voices, but when they looked up to Rivvy's grandfather as he stood on the balcony, as they gazed up at the head of their conclave, there was no joy, no warmth. None of the excitement and adrenaline Rivvy usually associated with a hunt.

No, in the faces that all turned towards her grandfather, there was nothing but steely resolve and apprehension, and this alone was enough to turn Rivvy's blood to ice.

"We've sent out scouts." Henry Cartwell was saying hurriedly, hovering like a fly at her grandfather's elbow. "To see how many. They haven't returned."

"We'll take no chances." Her grandfather said, ignoring Henry completely and raising his voice so the entire conclave could hear, even from below the balcony. "Ready yourselves for battle. We won't make a move until we know what we're up against." There was a murmur of agreement, the distinct sound of people checking weapons. "River," Rivvy's grandfather turned to her, his voice becoming quiet. "Wake your brother and bring him to the library. Both of you need to portal to Idris tonight."

"What?" Rivvy gaped at him. "No! Send James, but I'm staying."

"It's too dangerous." Her grandfather replied, dismissively. "You'll get in the way."

"I'm sixteen, grandfather!" Rivvy cried, not caring now about angering him. She glanced to Steven for support- he knew what she could do. He'd seen her train, he knew. "I've been hunting for years, I can handle myself."

"You're inexperienced, and we don't know what we're facing." It was Steven that replied this time, calm as ever. Rivvy just stared at him, the betrayal rendering her speechless. What were they thinking? If it really was an army, they needed all the shadowhunters they had, and that meant her. Wasn't this what they'd trained her for?

"But-"

"Go and get your brother." Her grandfather said, and the authoritative tone was back, marking the end of discussion. Rivvy simply gave him a look of pure venom, resisting the urge to hiss. Even she knew how ridiculous she must look to Henry Cartwell and the other two shadowhunters- she was small for sixteen, and still in the floral, butterfly-sleeved dress and hat she'd dressed in that morning. To them, she may as well be a little mundane girl, weak and frilly. She scowled one last time at them all before turning on her heel and stalking for the stairs. Let them think that, she thought sourly, just let them wait and see.