A fist hammering on the door woke Maura from her slumber.

"Gas!" came the cry.

Maura stumbled to the door and found Peter Lewis, a Private attached to C Company's headquarters, panting on the stoop.

"Gas attack up the lines!" he said. Maura didn't need him to elaborate. Already fully dressed she followed him at a dead run down the steps and up the street.

Milling soldiers looked up in surprise as Maura and Peter tore past them. As they ran the two were joined by several other men – medics – all merging to pelt towards the aid station. The road was suddenly filled with running bodies, dodging around the gun limbers and narrowly avoiding a column of marching men. Maura saw an artillery horse spook out of the corner of her eye, heard the soldier astride it shout out angrily, but her searing lungs prevented her from shouting an apology as the aid station finally came into view.

In the distance she could see the first field ambulance bumping off the road to the frontline. A column of men staggered behind it, some holding the shoulders of the men in front.

"What … gas … is it?" Maura rasped around the burn in her chest.

"Mustard," came Peter's reply. His long, skinny legs carried him ahead of Maura and he was the first of the group to arrive at the aid station. Maura wasn't far behind, and she found that Korsak had managed to clear most of the beds in the time she had been asleep.

The grey-haired, bearded native Bostonian was loudly directing a team of medics as they set up an extra couple of beds at the end of the tent.

"They've just come off the road," Maura alerted him breathlessly. Korsak turned and saw her, nodded once, then directed the medics to intercept the incoming flood of gas victims.

Maura had dealt with gas before, and mustard gas was the worst. Heavier than air it crept like a hunting cat across the battlefield and stealthily settled in every depression in the landscape, where it remained for a long time after its release. Soldiers would often take shelter in a shellhole only to find a cloud of deadly mustard gas lurking in the bottom. Entire trenches had to be evacuated after its use. Thick and greasy it attacked the skin, eyes and lungs of its victims, blistering around the mouth and in every crease of skin beneath the man's clothing.

The only treatment they could provide at the station was a bath in hot water and soap to rinse the chemicals from the skin, and eye rinses to prevent infection and blindness. The men would be in agony long after they left. Many would be scarred for life. Gas victims were the worst to treat. Men and boys coughing and choking, the skin on their faces and bodies stretched tight, all of them screaming in fear and pain. A man with a flesh wound from shrapnel understood what might happen to him, but gas was a new weapon. And the fear of the unknown was greater than the fear of death.

Maura dreaded the next few hours, but she found her apron and pulled it on nonetheless. It was then that Korsak clattered to her side, depositing a blood-stained tray of utensils and bandages onto the table beside Maura.

"We've been reinforced," were the first gruff words from his mouth.

"What?" Maura asked blankly, deftly tying her apron strings behind her back and tugging it down her hips.

Korsak flicked his eyes to a corner of the tent. Maura lifted her head and saw a huddle of young women gathered there, staring wide-eyed at the few remaining wounded. Maura's gaze bounced from face to face, then was drawn inexplicably to a tall, thin, sharply featured woman who stood a few feet away alone.

"They only just arrived," Korsak said.

The woman, sensing Maura's scrunity, looked up and Maura was met with a pair of stunning, dark, liquid brown eyes. Maura felt her breath catch. Her heart leapt against her ribcage. It unnerved her.

"Well they're in for a fucking shock," she replied, tearing her gaze away from the woman and reaching for a stack of clean rags.

Seconds later the quiet tent was thrown into chaos as dozens of gassed men staggered through the open flap. Maura's autopilot kicked in. She rushed from bed to bed, directing the new nurses to strip them of the contaminated clothing and begin to sponge-bath the men. She pointed out the problem areas – under the jaw, the armpits, the folds of the elbows and knees, and the crotch. One or two of the young women baulked at handling the men's genitals and Maura had to tell them to get over it.

"You're field nurses," she snapped, whisking by with an armful of discarded uniforms. "Do your damn jobs!"

She passed the woman whose gaze she'd met earlier bent over a soldier who couldn't have been older than eighteen. He was crying with fistfuls of the woman's apron in his pinched hands, staring unseeingly at the roof of the tent.

"You're okay, you're okay," the woman said to him, her voice deep and gravelly. "Tell me about yourself. Where are you from?"

"L-london," the boy stuttered, spluttering as he struggled not to cough.

"London! I've never been there."

"A-are you … American?" he hacked.

The woman smiled. "Yes. I'm from Boston."

"W-where's t-that?"

"Near New York."

"New York," the boy replied wistfully, sinking back against the stretcher.

Maura continued to the table where the uniforms were being dumped and retrieved a fresh bucket of water, returning to the Boston nurse.

"Here," she said, replacing the dirty water with the fresh bucket.

"Thanks." Maura's chest tightened at the smile the woman gave her. A few strands of dark, curly hair had escaped from beneath her cap and hung across her thin face. Maura had to force herself to turn away. As she did she saw a dark skinned man stagger into the tent under the weight of an unconscious medic.

"Maura!" he called in French tinged with a thick Moroccan accent.

"Badr!" she replied, hurrying to his aid. Together they managed to get the comatose man onto a stretcher bed. Maura noted blood dripping from beneath a bandage wrapped hastily around the man's thigh.

"Shrapnel on the high road," Badr Givre gasped. It was then that Maura realised it was Badr's partner George on the table. George drove the ambulance that he and Badr operated together. She'd only met him a few times, but he and Badr were usually inseparable.

"Quick, go find Korsak," Maura said urgently, pressing her hands to the gushing wound in a futile attempt to stem the flow of blood. Badr nodded and rushed off to find the doctor.

It took too long. Maura's arms were dead by the time Badr returned with Korsak, and so was George. He'd bled out in minutes. Korsak confirmed it as Maura cleaned her hands on her apron.

"Get his meat ticket," Korsak said, and Maura reached to remove the aluminium disc from the leather throng around the young British man's neck. But a dark hand stopped her.

She looked up and met Badr's steady gaze. He wasn't much taller than her, and was lithely built. His large hand encircled her wrist easily.

"No. Let me," he said softly. Maura hesitated, then nodded. Badr tugged the leather throng out from beneath George's tunic and removed one of the discs, leaving the other on the throng which he tucked back under George's clothing.

"I'll go find a cart -" Maura began.

"No. I will carry him. It isn't far," Badr replied. He bent and scooped up his friend. "Thankyou, Maura," he said, nodding to her. Then he turned on his heel and strode from the tent.