Jem took too deep a breath and started coughing, setting off a chain reaction of pressure sensors on the CPAP. Bloody thing, she wrote. How’re my sats?

The monitor was out of sight behind her. Rosie spent a couple of seconds pretending to analyse it so Jem wouldn’t guess how closely she’d been keeping tabs. By this stage, she could have provided a detailed graph broken down into half-minute increments and featuring all the occasions where Jem had got lazy, dipped below eighty-five percent, and given Rosie a bout of palpitations.

“Hovering around ninety-four, occasionally peaking at ninety-five,” she said. “You’re officially cooking on gas, Ms. Pardon.”

Jem made an okay sign. I could murder a brew.

“I bet you could. Shall I see if your doc—” Rosie broke off when she saw Harriet approaching the cubicle. “Holy shit. Did I summon her?” she whispered, and Jem spluttered a laugh.

OW, she scribbled, her hand splinting her overworked ribs.

“Sorry.” Rosie pulled at her scrubs top until its creases disappeared, and hid her filthy socks beneath a blanket. Harriet had extended her shift to oversee Jem’s treatment, but she didn’t have a hair out of place, and every time she walked in she brought with her the scent of fresh strawberries.

“You look perkier,” she said, setting her steth on Jem’s chest. “Try not to cough. I like having eardrums.” She sat on the bed when she’d finished and read through the latest obs. “You’re still tight on your left side, but I want to try you on nasal O2 and nebs and see if we can keep your sats where they are. Do you feel up to that?”

Jem wrote YES and underlined it.

“Good,” Harriet said. “Give me ten minutes to get everything written up.”

She was back in five, armed with a lidded beaker of tea and a packet of biscuits.

“You know it’ll feel weird, so don’t panic,” she said, uncoupling the straps and easing the mask from Jem’s face. She placed a thin plastic tube below Jem’s nose and adjusted its flow of oxygen, her eyes never leaving Jem as she did so. Rosie inched forward in her seat, waiting for something terrible to happen, for Jem to turn blue or start gasping or lose consciousness, but Jem took a few deliberate breaths and then held out her hand for the brew.

“It’s as if we’ve done this before,” Harriet said, tilting the beaker for Jem to take a sip.

“Uncanny, isn’t it?” Jem’s reply was rough and scratchy, as if someone had sandpapered her vocal cords. “Thanks, Harriet.”

“My pleasure. You’re doing really well. There’s no HDU bed for you at the moment, but at this rate we’ll be able to admit you onto Respiratory instead.”

“Sounds like a plan.”