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Chapter 59

Poeglared at the isolation ward’s video monitor as if it were personally responsible. It wasn’t hyperbole – the Botanisthadgot to Karen Royal-Cross. She was dying. Twenty-four hours earlier, a urinary biomarker had tested positive for ricinine, the alkaloid in the castor bean plant, and the only reliable way of verifying ricin poisoning. Within two hours she’d started to vomit and her bowel movements became looser and more frequent. Her temperature spiked and she developed a cough. She was now at the stage where her lungs were filling with liquid. Her skin had taken on a bluish pallor as the blood gradually became deoxygenated.

‘She’s deteriorated sharply in the last couple of hours,’ Doctor Mukherjee said. ‘We’re still doing everything we can. She’s being pumped with fresh blood, saline. A few other tricks we learned during the COVID crisis.’

‘Can you save her?’ Poe said.

‘No. She has multiple organ failure. She’ll be dead by the end of the day.’

Flynn was in a meeting with Detective Chief Superintendent Mathers and Bradshaw was copying the infectious diseases unit’s video files to her computer. It meant that when Karen Royal-Cross died, they could decamp and let the unit return to their day job. Doctor Mukherjee was keen to help. The only people who had been in contact with the patient were his staff. He didn’t want them falling under suspicion.

Poe decided to review the footage of the last twenty-four hours. He wasn’t expecting to see anything, but he couldn’t think what else there was to do.

Contact with Karen Royal-Cross had been kept to a minimum. Partly because it was an ongoing police operation and partly because she wasn’t being treated for anything. Essentially, the doctors and nurses were feeding her and monitoring her urine. Each time someone entered the isolation ward, Poe paused the screen before they had masked up. He then compared their face against the corresponding photograph on the hospital’s HR database. He checked them all on the way in, all on the way out and saw nothing suspicious.

The first sign that something was wrong with Karen Royal-Cross was when she said the shepherd’s pie she had eaten for lunch had given her an upset stomach. Doctor Mukherjee had immediately asked her to urinate. As soon as the urinary biomarker tested positive, the infectious diseases unit kicked in with their protocols.

Despite the near-hysterical Karen Royal-Cross refusing to acknowledge she was ill – it was more fake news – a doctor had managed to insert a drip and was able to start flushing her system.

But it wasn’t long before the gravity of the situation became apparent to her. She begged for help. She issued threats to sue, threats of violence, even some racial slurs. Inside the isolation ward, the doctors and nurses remained calm. They spoke to her in relaxed, measured tones. They told her she was ill, but they would be doing everything possible to keep her alive. It was what they were trained to do – stress reduced the body’s immune system.Outsidethe isolation ward was a different matter entirely. Not panic, more a sense of disbelief. Like they’d been told a well-liked colleague had been crushed to death by a block of frozen urine ejected from a jumbo jet’s toilet.

Mathers had detectives checking the kitchens in case the Botanist had somehow managed to slip something into Karen Royal-Cross’s meal before it had arrived on the ward. Poe didn’t think that was what had happened. Her meals were standard hospital slop, plated under the watchful eye of a detective sergeant. Her custard was ladled into her bowl from a big vat, her shepherd’s pie was spooned from a tray. None of the other patients had fallen ill, so it hadn’t been tampered with at source. It was possible the Botanist had got to her meal after it had been dished up, but Poe didn’t think he played that way. It was too … close. Too immediate. Poe didn’tthink the Botanist was anywhere near his victim when the fatal dose was delivered.

Doctor Mukherjee slumped in the seat beside him.

‘How is she?’ Poe asked.

‘Deteriorating. I expect her liver, spleen and kidneys to stop working any time now. She’s on a ventilator as she can’t breathe on her own.’

‘How long?’

‘Minutes, not hours. She’s been given a large dose. Death is inevitable.’

Poe didn’t doubt it. Ricin was one of the few poisons without an antidote. Accepted treatment was to provide supportive medical care. Fluids for dehydration, mechanical assistance for breathing. Drug therapy to treat seizures and low blood pressure. After that, the body was on its own.

‘How easy is it to make ricin?’ Poe asked. Bradshaw had explained the science, but the complexity was subjective. She’d said it was easy, but he shouldn’t try it.

‘You need castor beans, obviously,’ Doctor Mukherjee said. ‘A solvent to extract it. Some basic lab equipment. I’m told it’s not a difficult process.’

‘Could you do it?’

Doctor Mukherjee frowned.

‘I’m not asking if you did,’ Poe explained, ‘I just want to know who could. I need to understand what level of expertise is needed.’

‘With the right equipment, yes,’ Mukherjee said. ‘I believe I could make ricin.’

‘Who else?’

‘Anyone with access to the internet.’

‘That’s not true though,’ Poe said. ‘Because of the Counter Terrorism and Border Security Act, detailed instructions aren’t as readily available as you might imagine. And the security services routinely monitor who’s accessing sites that do still have recipes.’

‘Let’s think about this logically then. Anyone employed in a discipline where a working knowledge of chemistry is a prerequisite would understand the theory.’

‘Chemical engineers?’

‘Almost certainly.’