She rolled back towards the bed, shaking herself free of the curtain and only then realising she had pulled it down. Jessica lay on her back, staring at the ceiling. She could feel the weight of her phone in her hand and shone it upwards, trying to count to ten and calm her thoughts. When she reached five, she twisted her body around until she was on her knees, using the corner of the bed to raise herself up.

Even with small breaths, the air instantly felt harder to digest. She knew she had to stay low, so she crouched and stepped across to the window. As she turned, she peered towards Adam. He was spread-eagled on his back, his eyes closed, one arm hanging limply off the bed. She knew she would have been in tears at any other time but her throat was so raw that it felt as if there was no moisture in her system at all.

Jessica pressed herself against the window, the glass cool against her skin. She let the phone drop onto the window sill. Her eyes again felt heavy, as if willing her to sleep, but she put a finger and thumb above and below each eye, physically pulling them apart. Jessica coughed heavily, huge heaves of thick phlegm rolling up her windpipe into her mouth before she spat it onto the floor. Her throat was still sore as she pressed her thumb onto the button of the window’s locking mechanism.

Usually, she would have been able to push it in and twist the handle. As she tried, Jessica felt a slow sense of panic flowing through her as she realised the button wasn’t giving way. With the tip of her thumb, Jessica could feel the outline of a small keyhole and recalled that Adam made a point of locking all the windows when they weren’t at home. She remembered him telling her the previous weekend just before they left the house that he was going to check everything was locked. She’d sat in the car complaining about the length of time he was taking but now wished she had gone with him.

Jessica fell to her knees, partly through exhaustion but also because she knew she had to stay low. She reached onto the sill, fumbling for her phone and pulling it towards her. She shone the light along the length of the frame, hoping to see the key somewhere nearby. She could picture what it looked like. It had been a silver colour at some point but was now faded to a scuffed grey and was barely larger than the fingernail on her big toe.

Just in case she had somehow swept past it, Jessica ran her hand the full length of the sill but there was nothing there. She sank down until she was sitting directly under the window facing the rest of the room. A thought ran through her head that she could smash the window if she could find something heavy enough but the part of her brain still thinking rationally remembered a locksmith once telling her how hard it was to get through double-glazing.

She closed her mouth and tried inhaling steadily through her nose. As she shone the light upwards, she could see there was a greater amount of smoke drifting around the top of the room. Jessica couldn’t resist shining the light back to Adam’s body. He hadn’t moved since she had tried to rouse him but she crawled back across to the bed and pulled herself near to him, placing her ear close to his mouth. She was hoping to hear him breathing but there was nothing. Her mind drifted back to primary school where her class had been taught how to take a pulse. She had been at the back punching Peter Jenkinson hard on the shoulder to see if she could bruise him. He would grimace and then punch her back. Jessica wished she had paid attention. Even through the police training, taking a pulse was something she had never mastered.

Jessica shone the light back down to his chest and felt her heart skip as she watched his chest rise a tiny amount before falling again. She rolled onto her back, resting her head next to Adam’s and trying to think where he might have left the key. It had to be in the room because it didn’t fit any other window. She knew what Adam was like and leaving the key near to the lock so he didn’t lose it was something he would do.

Although he would have left it close, he definitely wouldn’t have left it within sight. She remembered telling him about a case where someone had used a hook to steal car keys through a letterbox and he had made a point of keeping things out of sight ever since then.

Jessica could still hear beeping from below her, knowing fire engines would arrive without sirens at this time of the morning. She closed her eyes, fighting the tiredness but trying to picture the layout of the room. Adam slept closest to the window, which meant the key would almost certainly be somewhere in that half of the room.

She slid onto the floor, opening her eyes and lying as flat as she could comfortably manage. She doubted he would have left the key in the wardrobe at the foot of the bed and, if it wasn’t on the window sill, the only other place it was likely to be was the bedside table next to him. As Jessica pressed her palms into the carpet, she could feel the heat from underneath. It was almost too hot to touch but Jessica’s aching limbs wouldn’t allow her to move any quicker.

Slowly, she edged along the side of the bed until she could reach out and touch the cabinet. Somewhere along the line she had dropped her phone but she wasn’t sure she had the energy to find it. Her eyes felt painful and she could not force them to stay open.

Jessica ran her hands across the front of the wooden bedside table and fumbled the top drawer open without opening her eyes. She reached inside, pulling out socks and underwear, letting them drop to the floor and listening for the clang of a key.

As she removed the final item, Jessica smoothed her hand along the inside of the drawer but could not feel anything metallic. She shuffled back to the floor, pushing the items of clothing around and groping underneath in case she had accidentally pulled out the key already.

Feeling like giving up, Jessica returned to the cabinet, opening the next drawer and reaching inside to feel metallic bottles that must have been deodorant cans. She forced her eyelids apart but her head was heavy and the rush of air seemed as if it was stabbing her in the eyes. With her phone lost, there was barely enough light from the window to see the contents of the drawer but Jessica fumbled for each item one at a time, taking out the toiletries and dropping them onto the floor.

As the final one fell, the rush she had felt moments ago disappeared, almost as if it had a physical presence which had been taken away. Jessica’s mouth was parched and she wanted to cry so much that her stomach ached. She rested her forehead on the top of the cabinet, reaching in the drawer and tracing along the edges. There was nothing at the front but as she reached towards the back left corner, her fingers felt something cool.

She tried to tell herself to stay calm but, in her rush to pull the key forward, Jessica could only shunt it further into the drawer. She could feel her entire arm shaking with anticipation and frustration and settled herself to try again, this time taking the small object between her thumb and forefinger and moving it into her palm.

For a moment, Jessica wanted to relax and enjoy the success of the moment but the warmth of the floor was telling her she had to keep going. She used the bed to help pull herself up and felt her foot touch her phone. Bending down, she picked it up and staggered back to the window, dropping the phone and key on the sill.

Under her breath, she mumbled ‘concentrate’ but instantly wished she hadn’t as it launched her into another coughing fit. Jessica could feel the pressure through her chest. Part of something was coming up her windpipe each time she coughed. Again, she rested her forehead against the glass, allowing its coldness to keep her alert. For the first time since she had woken up, a chill went through her.