Agent Okeke frowned. ‘I didn’t choose the post. I was loaned out to Interpol.’

  ‘From where?’ asked Melanie.

  ‘The counter-terrorism squad,’ said Agent Okeke.

  ‘And this wasn’t a change you chose?’ guessed Melanie.

  Agent Okeke glowered. ‘Interpol requested experienced investigators. It was thought that I would benefit with some time away from my unit, while I do re-retraining to deal with my anger-management issues.’

  ‘What anger-management issues?’ asked Friday.

  ‘I punched a fellow officer in the face,’ said Agent Okeke.

  ‘I can see how that would be an issue,’ said Melanie.

  ‘Why?’ Friday asked Agent Okeke. ‘Did you punch him, I mean?’

  Agent Okeke sighed. ‘We were on a big raid. A terrorist cell had set themselves up in a terrace house on the outskirts of Paris. There was a lot going on. Several different agencies with dozens of officers were involved. The terrorists tried to run for it. They were trying to destroy evidence. During the commotion, I got arrested.’

  ‘Oh dear,’ said Melanie.

  ‘That’s not the bad part,’ said Agent Okeke. She grimaced angrily, apparently reliving her rage in her own mind. ‘It was eight hours before my fellow officers realised the mistake. I had to spend eight hours in the cells with every other miscreant arrested in Paris that night, and let me tell you they all realised who I was in the first eight seconds.’

  ‘That sounds unpleasant,’ said Melanie.

  ‘When there was a shift change the following morning, the mistake was realised and I was released,’ said Agent Okeke. ‘My colleagues in the counter-terrorism unit were just coming back in to work, coffees in hand, having had a good night’s sleep. They got one look at me after a night in the cells and they laughed. They actually laughed. Even my commanding officer thought it was funny.’

  ‘I suppose it is important to maintain your sense of humour in difficult times,’ said Melanie.

  ‘He didn’t think it was funny when I punched him,’ said Agent Okeke. This was the first time they had seen her smile. It was a small smile but she clearly enjoyed the memory.

  ‘Oh dear,’ said Melanie.

  ‘I shattered the bone in his nose,’ said Agent Okeke. ‘He needed plastic surgery to reconstruct it. He still has to wear a bandage over it on sunny days to protect the wound.’

  ‘So were your anger-management issues caused by this incident or exacerbated by this incident?’ asked Friday.

  ‘Both,’ said Agent Okeke.

  ‘Okay,’ said Friday.

  Friday and Melanie decided it was best to let Agent Okeke brood in silence for the remainder of their drive into the city.

  Paris is one of the most beautiful cities in the world. Napoleon III may have been less successful than his uncle at taking over Europe, but he did do a fabulous job of rebuilding the capital. Wide boulevards and lovely public parks are surrounded by elegant nineteenth-century public buildings. But that’s in the centre of Paris. The rest of the city is a sprawling mass of suburbs, that looks much like the outskirts of every other major European city. There are lots of tenement houses, bustling factories and functional institutions, where real people get on with day-to-day life away from the tourists.

  ‘I have enrolled you in the Art Institute du Louvre,’ said Agent Okeke. ‘It is a fine arts college that teaches short courses for students from other institutions. That’s what you’ll be doing. It’s a six-week holiday program, run in the winter semester break. You will learn from the great masterpieces of the Louvre by going to the gallery every day for lectures and to sketch the artworks.’

  ‘That sounds like fun,’ said Melanie.

  ‘But how will that help investigate a forgery that took place one hundred years ago?’ asked Friday.

  ‘Because we want eyes on the ground,’ said Agent Okeke. ‘The Louvre Museum is a revered institution in France. It has great prestige in the art world, but it is also a financial powerhouse for tourism. Ten million tourists go to the Louvre every year to see the Mona Lisa. That one painting is more than a point of French pride. It is a lodestone for our economy. There is a lot more at play than one thief. There’s politics and power and greed.’

  ‘But I’m good at solving mysteries,’ said Friday. ‘I can’t help with politics.’

  ‘You aren’t here to solve anything,’ said Agent Okeke. ‘You are here to be a cog.’

  ‘A cog?’ said Friday.

  ‘Are you sure you know what that word means?’ asked Melanie.

  ‘I know what a cog is!’ said Agent Okeke. ‘I’m saying that you are a small part of a much bigger machine. The machine is the investigation. You must do your job so the machine can work. Your job is to watch and accrue information.’

  ‘Okay,’ said Friday. ‘I can do observation. That’s a principal part of scientific investigation. I know how that works.’

  ‘We need eyes on all the workings of the gallery,’ continued Agent Okeke. ‘If this is an attempt to discredit the Mona Lisa’s authenticity, it could be a trap. We need to be vigilant. Art is all about pranks and irony now, thanks to that idiot Giorgio.’

  ‘You think he’s involved?’ asked Friday.

  ‘It’s just the sort of stupid thing he loves,’ said Agent Okeke. ‘Diminishing the authenticity of a masterpiece revered by the establishment. It contrasts perfectly with his mission to raise up graffiti to be regarded as high art.’

  ‘Really?’ asked Friday. ‘I thought he was just an artistic version of a socialite. A playboy with pretensions.’

  ‘Last year he ran Vincent Van Gogh’s painting Sunflowers through a woodchipper,’ said Agent Okeke.

  ‘What?!’ exclaimed Melanie.

  ‘It was a hoax,’ said Agent Okeke. ‘Or as he called it, “a political act of performance art”. He used a copy. That’s just the type of stunt he loves. Something that challenges fundamental assumptions about the value of art, as well as making everyone in the art establishment so horrified they pee their pants.’

  ‘So we’re not just keeping an eye on the Mona Lisa,’ said Friday. ‘We’re keeping an eye on the people looking at the Mona Lisa?’

  ‘Exactly,’ said Agent Okeke. ‘No-one will notice you because you’re teenagers and no-one likes teenagers.’

  ‘Hmm,’ said Melanie. ‘You’re very frank, aren’t you?’

  ‘I speak the truth,’ said Agent Okeke.

  ‘Yes,’ agreed Melanie. ‘But there are always lots of versions of the truth. Yours is very angry.’

  Agent Okeke glanced in the rear-view mirror. If looks could carry a handgun, Melanie would have been in a lot of trouble.

  ‘How do we contact you if we have any information?’ asked Friday.

  Agent Okeke sighed. ‘You go to the gift shop and buy a postcard.’

  ‘I’m sorry?’ said Friday.

  Agent Okeke sighed even louder. ‘My cover is to work in the gift shop in the lobby of the Louvre’s main entrance.’

  ‘Oh dear,’ said Melanie. ‘If arresting terrorists didn’t work out for you, I can see how customer service is going to be a struggle.’

  ‘You’ll be okay,’ said Friday. ‘No-one expects French shop assistants to be nice.’

  The Art Institute du Louvre was not as glamorous as the name suggested. True, it was just a hundred metres from the famous and beautiful art gallery, but that one hundred metres held an entire city block of other buildings. It may as well have been a hundred kilometres. In Paris, the aura of glamour doesn’t extend far. Breathtakingly beautiful architecture is cheek by jowl with poorly maintained, graffiti-covered tenements that for some reason always smell like a public toilet. Agent Okeke dropped them off outside just such a building.

  ‘Are you sure this is the right place?’ asked Friday, looking up at the narrow five-storey building cramped between a souvenir store and a tobacconist.

  ‘I thought you were the great detective prodigy,’ said Agent Okeke. ‘Can’t you detect the plaque on the door?’

  Behind a tangle of abandoned electric share scooters, there was a very dirty plaque on the door that was probably brass, but some sort of filth was spattered across it. It read, ‘Art Institue du Louvre – Student Accommodation’.

  ‘I saw the sign,’ said Friday. ‘I just thought it might be wrong.’

  ‘You aren’t coming in with us?’ asked Melanie.

  ‘Of course not,’ said Agent Okeke. ‘It would compromise your cover.’

  ‘I guess we’ll see you at the Louvre then,’ said Friday.

  ‘Whatever,’ said Agent Okeke. ‘I’m your handler, not your mother.’ She threw the car in gear and sped away.

  Friday watched the car take the corner too quickly, nearly killing a tourist on an e-scooter. ‘She’s actually warmer and chattier than my mother,’ Friday observed.

  The inside of the Art Institute building was only moderately less disappointing than the outside. The lobby was a narrow room, half of which was taken up by a staircase leading to the dormitories above. The marble floor was superficially clean, but everything else was old and worn. The white walls were not as white as they would have been two decades ago when they were last painted. Tucked in underneath the staircase was a small porter’s office. The woman who worked there didn’t look like she had ever walked up the staircase in her life. She was staring at a video on her computer on her desk. She barely acknowledged Friday and Melanie when they introduced themselves. She just pointed to the staircase above her head and said, ‘Fifth floor.’

  Friday looked at Melanie’s enormous suitcase. ‘If we grab an end each and take lots of rest breaks, I think we can make it.’

  ‘This almost makes me regret packing so many shoes,’ said Melanie.

  Ten minutes later, after a great deal of trudging and heavy breathing, Friday and Melanie finally dragged the suitcase up onto the landing of the fifth floor. There was only one door. They tried knocking but no-one responded. They could hear voices from within.

  ‘Come on, just open the door,’ someone was yelling, but it was muffled as if it was being yelled from the far end of the apartment.

  ‘Do they mean us?’ asked Melanie, indicating the door she and Friday were standing in front of.

  Friday shrugged. She tried the door handle. It was unlocked, so they both entered.

  They passed through a short passageway, with a coat rack and backpacks dumped on the floor, and found themselves in a large open-plan room with a lounge area on one side and a kitchen on the other. Two teenage boys were sitting on the enormous L-shaped sofa. One was studiously drawing on a sketchpad. The other seemed to be napping.

  ‘Hi,’ said Friday. ‘Are we in the right place?’

  The napping boy opened his eyes. Friday noted that they were dark brown and very nice to look at. Although the dark rings under his eyes indicated that he was tired. ‘Have you just come off a double shift making pizza?’ she asked.

  ‘What?’ said the boy. He was startled. ‘Do I know you?’

  ‘Not yet,’ said Friday. ‘But I can deduce many things about you. You’re wearing a polo shirt that says, Giuseppe’s Pizza, the best pizza in Paris, which could be merchandise, but it is bright red. That’s not a colour a fashion-conscious teen would choose to wear voluntarily, so I assume you work there.’

  The boy looked down at his shirt and frowned.

  ‘And the shirt is faded,’ continued Friday. ‘It’s been washed repeatedly, which suggests that you are an experienced employee.’

  The boy smiled proudly at this.

  ‘The type of employee a boss would ask to stay on when someone doesn’t turn up for the morning shift,’ said Friday. ‘Of course, you could be a delivery person, but the flour stains on your shirt suggest that you’re actually involved in preparing the pizza.’

  The boy hastily tried to brush the flour off his shirt.

  ‘And your highly developed carpi radialis muscles,’ said Friday, pointing to his forearms, ‘are consistent with someone who spends a lot of time kneading dough, which I know, from when my parents forgot to do the grocery shopping, is surprisingly hard work.’

  ‘That’s amazing,’ said the boy. ‘That’s exactly what I do. I take the dough and shape it into pizza bases. Giuseppe is my uncle. He gets me to stand in the window while I work. The tourists like watching me throw the pizza bases around. My name is Roberto.’

  ‘Hi, Roberto,’ said Melanie.

  ‘Now do Adam,’ Roberto urged Friday, pointing to the serious boy sitting next to him. ‘Tell us what you can figure out about him.’

  ‘Deductive reasoning is not a party trick,’ said Friday.

  ‘It kind of is,’ said Melanie. She plopped down on the couch next to Roberto, waiting for Friday to perform.

  Friday turned to inspect Adam. He glanced up and noticed that the other three were staring at him.

  ‘What’s going on?’ asked Adam.

  ‘Go back to your drawing,’ said Roberto. ‘This girl is going to figure out everything about you just from looking at your clothes.’

  Adam looked alarmed by this prospect.

  ‘Grey sweater, button-down collar, jeans and wire-framed glasses,’ listed Friday. ‘The most distinctive thing about your clothes is they are ironed. Young people don’t iron. Especially not young art students. You dress like a law student. Although they don’t iron either.’

  ‘I get my clothes ironed for me,’ said Melanie.

  ‘Yes, but if an art student was as rich as you and had a maid who ironed their clothes,’ said Friday, ‘they would then purposefully crumple their clothes, so they’d fit in. This level of fastidiousness in someone so young speaks of a deep-seated psychological need to bring order and control to their life, and the only people who seek order that much are people who have never had it. If you really wanted order in your life, you wouldn’t be an art student, unless you were so talented it was inescapable.’

  ‘You should mind your own business,’ said Adam.

  ‘Hostility,’ said Friday. ‘Perhaps that indicates parental issues. Or perhaps you simply love art, you’re in a flow with your drawing and I’m irritating you.’

  ‘She’s got you bang on,’ said Roberto.

  Adam just glowered.

  ‘Are you with the police?’ Roberto asked Friday.

  Melanie had just had a sip from her water bottle. Roberto’s uncannily accurate guess made her inhale the water, which caused a coughing fit.

  ‘No,’ said Friday. She was startled to have her cover seen through almost immediately. ‘I’m an art student. I am good at observing things because I look at things all the time for reasons of art . . . nothing to do with crime.’

  ‘Okay,’ said Roberto.

  ‘I’m Melanie,’ said Melanie. ‘Sorry about Friday. She has very poor social skills. I think she was dropped on her head as a baby.’

  ‘She was?’ asked Adam. This made him look up from his drawing, perhaps to see if Friday had a misshapen head.

  ‘No, I’m joking,’ said Melanie.

  ‘Although it is possible,’ said Friday. ‘If you dropped an infant so that the prefrontal cortex of their brain was permanently injured, that could affect their lifelong ability to socially interact.’

  ‘Friday, this is an example of you not knowing how to interact appropriately,’ said Melanie kindly. ‘Too much detail about dropping infants the first time you meet someone is bad.’

  Friday nodded. ‘Noted. I should have been able to deduce that. I will endeavour to remember.’

  ‘Adam isn’t great with social skills either,’ said Roberto. ‘But he won the Prix de la Jeune Peinture Belge last year so he’s a big deal. It’s the most prestigious youth art prize in Europe.’

  ‘Could you stop telling people that,’ said Adam.

  Roberto rolled his eyes. ‘They can figure it out for themselves just by googling you. It’s rude to act like you aren’t who you are just to maintain a secret identity.’

  ‘Whatever,’ said Adam.

  ‘He’s just grumpy because the wifi is terrible here and he can’t FaceTime his girlfriend,’ said Roberto.

  ‘I am not,’ said Adam. ‘I don’t have a girlfriend.’

  Roberto had already closed his eyes. ‘Sorry, I mean your mother,’ he said. ‘I know you can’t bear to go a day without hearing her voice.’

  Adam picked up a pillow and smashed it into Roberto’s face. Roberto just laughed.

  ‘You can’t stay in there forever,’ a woman yelled from another room. Friday turned to the sound. On the far side of the common room there was a doorway leading to the bedrooms.

  ‘Go away!’ called another, younger voice.

  ‘What’s going on?’ Friday asked the boys.

  ‘The new girl locked herself in,’ said Adam, without even looking up from his sketchpad.

  ‘Really? That sounds very extreme,’ said Melanie. ‘Do tell.’

  Roberto opened his eyes again. ‘She was really unhappy with her dad when he dropped her off.’

  ‘He’s not going to be winning “father of the year” any time soon, that’s for sure,’ muttered Adam.

  ‘What did he do?’ asked Friday. She perched on the edge of the coffee table. She was reluctant to sit on the sofa. It looked like it would be hard to get back out of it once you were down.

  ‘She thought she was coming to Paris to stay with him for the winter holiday,’ said Roberto. ‘But he enrolled her here without telling her. They came straight from the airport. She thought she was going to be staying at his house.’

  ‘He said he has to work,’ said Adam. ‘And that she’ll enjoy it more here with people her own age.’

  ‘Yes, but that’s not the point, is it,’ said Melanie. ‘It’s the rejection that stings.’

  Friday had had many similar experiences with her own parents.

  ‘I know I’m not great at social skills,’ said Friday. ‘But wouldn’t it be best just to leave her alone? Let her have some quite time in her room?’

  ‘Oh, she hasn’t locked herself in her room,’ said Roberto. ‘She’s locked herself in the bathroom.’

  ‘And there’s only one bathroom,’ added Adam. ‘We all share it.’