Monday 26th September – 1 a.m.
‘Who the hell are you?’ The tiny yet forceful woman folded her arms in the lab’s doorway, staring at Nell and Rav. Alarmed, Rav turned to Aoife, who’d dashed back from the prep room expecting to be kicked out.
‘They’re helping me, Juliet. I needed to run some extra tests, and I knew this weekend wasn’t busy. And I’ll have some mass spectrometry to do tomorrow.’
‘You will?’ Juliet’s face transformed. ‘Oh, thank the Lord. I thought I’d have nothing on this weekend.’
‘Can I take them through and show them?’ Aoife asked, rewrapping Siobhan’s hair in cling film this time.
‘Sure you can. Just suit up properly. I got my blanks down to six PPT today.’
‘No way!’ Aoife high-fived her.
Nell frowned as she followed Juliet to the next lab and into the antechamber. ‘What does that mean?’
‘It’s a purity rating, if you like.’ Juliet pointed at the lockers for their mobile phones. ‘You can’t take any metal in here.’ She turned to Rav with a grimace.
Refusing to be sidelined, he lied, ‘I can walk. I just use this when fatigue sets in.’
Nell side-eyed him, but didn’t argue, and helped him pull on the coverall suit that everyone had to wear, along with booties, hoods, face masks and gloves.
As Rav staggered to his feet, gripping Nell’s arm so hard that her face drained of colour, he spotted the showers leading off from the chamber, and wondered what lay behind the lab doors.
‘We run blank samples alongside our real samples, to measure contaminants in the air that could affect our mass spectrometry readings. My contaminants are down to six parts per trillion. Which is very impressive, if I say so myself. And I thought it had happened on a day when I couldn’t even brag to anyone. But here you are!’ She grinned. ‘OK, you’re ready. Once you’re inside, move slowly, please. We must not disturb my six PPT air.’
‘That is incredible, Jules!’ Aoife said. ‘Ah, I see it’s on the board already!’ She pointed at the ‘Blanks’ board, rows of numbers beside names. Six was the lowest – by far.
‘Of course! I put a photo up on social media – let’s see what Durham make of that! ’
‘Uni rivalry?’ Nell whispered, shuffling along with Rav.
Aoife nodded. ‘They’re good. There’s a rumour of a five PPT.’ She grimaced and glanced at Juliet, who was checking a white machine.
Rav sat on the nearest wooden lab stool, and blinked as he looked around. Everything was white, clear or colourless: the tubes, the racks, the bottles, the lab benches, the walls. It felt like someone had bleached his eyeballs. The hum was louder in here, and Rav guessed it was a filtration system. And the fume hoods were more heavy-duty than usual.
‘You must deal with some serious chemicals in here, by the look of how you protect the lab workers.’ He pointed at the fume hoods.
‘That’s to protect my samples.’ Juliet tutted.
Aoife lay Siobhan’s sample on the bench, taping one end down, and Juliet hovered at her shoulder as she stretched out the long lock of hair alongside a ruler. The hair reached the full thirty centimetres.
‘I’m measuring the strontium in her hair so I can understand where she’s been, and can compare her travels to my Iron Age woman.’
‘How does it work?’ Rav asked.
‘Strontium is geospecific,’ Aoife explained. ‘It occurs everywhere, but in distinct, different amounts. And we absorb it in those signature amounts, in our teeth, bone and hair. As your hair grows about one centimetre a month, it locks in a strontium record of where you’ve been.’
‘It’s not perfect,’ Juliet added. ‘It depends on you eating food that has been grown locally, so for a modern population eating food that’s been flown in from all sorts of places, the signature can’t be as clear.’ She studied the lock of hair. ‘You’ll have thirty samples, here, if you’re careful. So that’ll give you her strontium records for the last thirty months that she was alive.’
Aoife nodded, setting out a rack of clear test tubes. She labelled each one to correspond to the length of hair, then carefully cut one-centimetre sections, using tweezers to place each section into the correspondingly labelled tube.
Watching, Rav realised he was holding his breath. Then realised that both his distance from the operation and his mask would prevent him from accidentally blowing any of the sample astray. It was so painstakingly precise.
‘Could you pass me the nitric acid?’ Aoife asked, pointing at the bench.
Rav looked at where Nell was sent to search: the clear bottled liquids looked innocuous enough. But the parade of skull and crossbones symbols emphasised just what an unpleasant line-up this was: alarming quantities of poisonous thallium beside the even more deadly hydrofluoric acid – the chemical used to dissolve bodies in Breaking Bad, which could kill you if you just coated the back of your hand with it – by sucking the calcium out of your bones. Shuddering, Rav watched Nell gingerly lift the nitric acid and pass it to Aoife, like she was carrying a bomb.
As Aoife opened the bottle, a gratifying plume of yellow-brown fumes unfurled, whisked away by the fume hood’s filter.
‘If I let my hair samples dissolve in the acid overnight,’ Aoife asked Juliet, ‘can I come back tomorrow to process the samples and start the mass spectrometry in the afternoon?’
‘Please do. I’m glad to have something to keep her busy.’ Juliet patted her precious machine.
‘How does it work?’ Nell asked.
‘Once the hair is dissolved, I’ll wash and filter the sample onto a resin. It’s a slow process because you need to wash the tubes and the resin carefully to prevent contamination. Once it’s all filtered and diluted to the right level, I can run my samples through the mass spectrometer and measure the strontium ratios.’
She pointed the square mass spectrometer and Juliet cleared her throat. ‘Or, rather, Juliet will. We’re not allowed to touch it.’
‘It’s a very technical bit of kit. And it has just one careful owner.’ Juliet had a protective stance as she stood in front of it.
‘So that will tell me the strontium ratios for each sample,’ Aoife continued, ‘and they’ll – hopefully – correspond to her geographic locations over the last two and a half years of her life.’
Aoife stared at the samples, swallowing, and Rav could see that this wasn’t a scientific project any longer. This was Aoife finding any way to have an insight – and connection – with the woman who might be her mother.
Nell gently tapped Aoife’s shoulder. ‘It’s time to start the electrophoresis. Do you want to join me?’
‘Yes.’ Aoife would have leaped up if Juliet hadn’t put out a hand, reminding her to move slowly.
In the antechamber, as Nell helped Rav to de-suit and return to his chair, he could see she was nervous. But she needn’t have worried. Back in the genetics lab, he peered at the tray, prodding it to see if the gel would wobble, like a chef testing a panna cotta.
‘Oh, this looks perfect.’
Nell took the tray to the large plastic chamber. It looked like a fridge’s salad crisper drawer, with a raised platform between two deep sections. Placing the tray of solidified gel on the raised platform, she removed the comb – checking the wells that the teeth had left in the gel, adding magenta dye and buffer solution.
Rav saw her hands shake as she drew the DNA sample up into the mechanical pipette and transferred it to the wells in the gel tray, labelling each with care. He could only imagine the weight of responsibility on her shoulders, while Aoife watched anxiously, chewing her nails.
Once Nell had filled the wells with Aoife’s sample, and Siobhan’s, she connected the electrodes to the chamber, dialling the power to 120 V.
‘Right.’ She looked up at the expectant faces that were staring at the submerged gel, then at her. ‘This will take about ninety minutes.’
‘Ninety minutes? ’ Aoife groaned. ‘You gotta be kidding me! This is torture!’
‘Yes, or alternatively, very quick.’ Rav heard impatience in Nell’s voice at Aoife’s ingratitude. ‘Almost instant, comparatively speaking.’
‘No, look, something’s happening already.’ Aoife pointed at the magenta dye beginning to migrate along the gel.
‘That just shows it’s working. Which is good.’
Rav smiled at the relief in Nell’s voice and tried to distract her. ‘Shall we hunt down a vending machine for a disappointing coffee?’
Aoife led the way to the ground-floor canteen and its hall flanked with machines. ‘The hot chocolate is reasonable. Don’t have the cappuccino.’
Following her advice, Rav ordered three tepid drinks while Aoife pilfered another machine for Hula Hoops.
As they killed the agonising minutes, Aoife showed Rav her map of strontium ratios – which she’d use to see where Siobhan may have travelled to.
But Nell was pacing, not really taking anything in. When Aoife went to get another round of drinks, he nudged Nell, trying to rouse her out of her worries.
‘What if it hasn’t worked?’ she whispered.
‘It wouldn’t be your fault. You said hair can be compromised when it’s been soaked.’
‘No, what if I’ve done something wrong?’ She stifled a yawn. ‘I’m so tired, I’m worried I could have made a mistake.’
‘You won’t have.’ When she huffed at him – apparently for thinking she was capable – he raised his hands. ‘You won’t make me believe you’ve done it wrong. Huff away.’
Finally, the clock showed 4 a.m., and they returned to the lab, where Nell removed the gel tray and disconnected the power.
‘There’s nothing on the gel.’ Aoife panicked. ‘Aren’t there supposed to be lines?’
Her panic made Nell initially doubt herself, dreading an error born of her fatigue. But then she sharpened her focus and shook away the foggy fear. ‘Ah. No. I’ll need to expose the gel to UV light before we can see them.’
‘Oh! In here. We have a chamber.’ She led Nell to the prep room.
Aoife looked agonised, having to wait yet more minutes for the lines of gene markers to appear on the gel. Nell studied them for a long time, checking with painstaking care. Then she let out a long, relieved sigh.
‘Well, we have a conclusive result.’
‘And?’ Aoife urged.
‘There’s no doubt, Aoife. Siobhan was your mother.’
Aoife let out a sob as she sank onto the lab stool. Nell put a gentle hand on her back as emotion poured out of the young woman, her head held in her hands.
‘Don’t get … me wrong,’ she said between sobs, looking up at them. ‘I’m glad to … know. For as long as I can … remember, I’ve ached to know her. But you’ve just told me … that my mammie is someone I’ll never have a chance to meet.’
Nell met Rav’s eyes. The look she gave him mirrored his thoughts.
Siobhan may be her mother … but if Siobhan was having an affair with someone – then who’s her father?