‘We need to ask ourselves, how far would they have thrown it,’ said Friday. ‘Far enough to get out the window, but they wouldn’t throw it with all their might, in case they hit a passing tourist in the head.’

  A group of young school children were approaching along one of the park’s paths. It would have been dangerous to be throwing rocks nearby.

  ‘So I think we can narrow it down to further than two metres from the window,’ said Friday. ‘But less than eight metres. That’s not too much area to cover.’

  ‘It’s still tens of thousands of stones,’ said Melanie.

  ‘Then we need a large search party,’ said Friday. ‘Saba, how good is your Norwegian?’

  ‘Pretty good,’ said Saba. ‘I take evening classes three times a week.’

  ‘Okay,’ said Friday. ‘Could you please ask those school children if they’d like to help? You could tell them you need to find a precious stone to rescue a princess from being locked in a dungeon by her angry father. Given the way children are indoctrinated through fairytales with morality stories fixated on royalty and precious objects, I would be very surprised if they were not excited to help.’

  Soon Friday, Melanie, Saba and sixty school children were on their hands and knees, scouring the gravel of the driveway for a stone with a hole in it. It took eight minutes before Bjørn, a seven-year-old with a very runny nose, found it. The other children were terribly disappointed and wanted Friday to throw it again so they could keep looking. Melanie made it up to them by buying them all ice blocks from a nearby van.

  Saba was delighted to have the mystery solved. She took great care in putting the Haakon Stone away safely.

  ‘You should use a hot glue gun to stick some diamonds to it,’ said Friday. ‘Ingrid might be a bit less lackadaisical with it, that way.’

  When they had settled into their room, Friday used Ingrid’s phone to call Bernie back and see how things were going in Bilbao.

  ‘You were right,’ said Uncle Bernie as soon as he picked up.

  ‘Oh good,’ said Friday. ‘So you arrested the conservator?’

  ‘Not exactly,’ said Uncle Bernie.

  ‘Surely you either arrest someone or you don’t arrest someone,’ said Friday. ‘There are no shades of grey.’

  ‘I confronted Dr Lopez,’ said Uncle Bernie. ‘She laughed in my face and confessed it all.’

  ‘That sounds good,’ said Friday.

  ‘Then she made a run for it,’ said Uncle Bernie.

  ‘She outran you?’ asked Friday. ‘Don’t you have lots of security guards on staff? She managed to outrun all of you?’

  ‘It sounds silly when you put it that way,’ said Uncle Bernie. ‘But the thing is, most security guards are men. And men are instinctively hesitant to crash-tackle women. Especially well-dressed, pretty women. And extra especially well-dressed, pretty women in wheelchairs.’

  ‘Oh,’ said Friday, catching on to what he meant. ‘She out-rolled you.’ Friday could visualise the awkwardness of the situation.

  ‘Also, there was just the sheer logistics of it – how do you crash-tackle a wheelchair?’ said Uncle Bernie. ‘I know I’ve never had to do it before. It’s not something they taught us when I went through the police academy. I used to play professional ice hockey. I know how to slam into an enormous man wearing a helmet, carrying a stick and with blades strapped to his feet, but it’s hard to know how best to slam into a metal wheelchair travelling at forty kilometres an hour.’

  ‘Surely she wasn’t going that fast?’ said Friday.

  ‘She wasn’t until she got to the ramps,’ said Uncle Bernie. ‘The Bilbao Guggenheim prides itself on its accessibility to the differently abled community. That means there are lots of ramps. Once she hit those, she was moving like a Formula One driver.’

  ‘So no one could stop her?’ asked Friday.

  ‘Oh, I stopped her,’ said Uncle Bernie. ‘I leapt over three balustrades, short-cutting the ramps and got to the lobby just after her. Once we were on the flat of the forecourt out the front of the museum, I started to narrow the gap.’

  ‘Well done, Uncle Bernie,’ said Friday. ‘I didn’t know your cardio-vascular system had it in it.’

  ‘As Dr Lopez slowed to turn around the giant sculpture of a puppy made out of flowers, I launched myself at her, smashing the wheelchair over, and knocked her to the ground,’ said Uncle Bernie.

  ‘So you did catch her?’ said Friday.

  ‘No,’ said Uncle Bernie. ‘A retired police sergeant visiting from Devon was so horrified to see a grown man crash-tackle a disabled woman, that he punched me really hard in the face and I was knocked unconscious. That’s when she legged it. We found her car abandoned at the port. She must have swapped to a boat. She could be anywhere.’

  ‘Wow,’ said Friday. ‘You lost the painting and you got a head injury. You’ve had a really bad day.’

  ‘Oh, this is more than one day’s worth of pain,’ said Uncle Bernie. ‘There are already videos of the whole thing all over social media. I’ve had disabled-rights groups calling me to complain all afternoon.’

  ‘Were any more paintings missing?’ asked Friday.

  ‘Yes,’ said Uncle Bernie. ‘We’ve found eight so far. She was really good, so they’re hard to spot. Luckily, she used cheap frames from Ikea, so we can work out which are forgeries by looking at the label.’

  ‘Have you been able to recover the originals?’ asked Friday.

  ‘No,’ said Bernie. ‘There’s nothing at her flat. But every Tuesday for the last eight weeks, she booked a courier to pick up a package and take it to a shipping office in Barcelona.’

  ‘That’s not good,’ said Friday. ‘That’s one of the busiest ports in the world. It’s the perfect place to smuggle things out of Europe.’

  ‘I know,’ said Bernie. ‘I’m trying to get hold of someone in customs to allow us to investigate. I’m going to have to travel there myself. I don’t suppose you could get here in time to come with me?’

  ‘I can’t leave now,’ said Friday. ‘But could you do me a favour?’

  ‘Sure,’ said Bernie. ‘It’s not like I’m busy or anything.’

  ‘Oh good,’ said Friday, not picking up on the sarcasm. ‘Could you run a check on Dr Klaus Finsberg?’

  ‘What’s he done?’ asked Bernie.

  ‘Probably nothing,’ said Friday. ‘But he works with Binky at Svalbard. I just want to make sure Binky is all right out there.’

  ‘I’ll run him through the database,’ said Bernie.

  ‘Thank you,’ said Friday. ‘And let me know what you find in Barcelona.’

  Ingrid was very excited when she arrived home the following day. She couldn’t stop hugging Friday and Melanie, she was so glad to see them. This made Magnus, her bodyguard, very nervous. He preferred people to stay two metres away from the princess at all times – especially Friday. He’d read an intelligence report about her detention for alleged terrorist activity and, unlike the judicial system, he did not believe in the principal of ‘innocent until proven guilty’. Eventually, Ingrid got fed up with Magnus. She made him go and stand ten metres away and stop glowering at her friends.

  ‘You must have terrible jet lag,’ said Melanie. ‘What is the time difference between Norway and the Galapagos Islands? It must be enormous. Wouldn’t you like to take a nap?’

  ‘Oh no,’ said Ingrid. ‘I flew first class. I slept the whole way on the plane. I want to take you to see the sights of Oslo!’

  ‘That sounds lovely,’ said Melanie. ‘We haven’t seen much so far. We spent a lot of time admiring your driveway yesterday.’

  Ingrid looked puzzled.

  ‘But never mind about that. Where are were going to go first?’ asked Friday, changing the subject. She didn’t want to get Saba in trouble. ‘The Viking Ship Museum? Vigeland Park? Akershus Fortress?’

  ‘I suppose we could go to those places,’ said Ingrid. ‘But I was planning to focus more on Oslo’s cultural highlights – starting with the best waffle shop in all of Norway!’

  ‘I like your plan,’ said Melanie.

  ‘Don’t worry, we will walk past historic buildings on the way,’ Ingrid assured Friday.

  ‘We’re walking?’ asked Friday. ‘Is that safe, with you being a royal princess?’

  ‘Oh yes,’ said Ingrid. ‘I am wearing my blue cardigan and glasses, so everyone will leave me alone.’

  Ingrid actually dressed a lot like Friday, except somehow, on her, a cardigan and jeans looked smart and elegant.

  ‘Does that really work?’ asked Melanie. ‘Surely everyone knows you wear a blue cardigan and glasses all the time.’

  ‘Well, yes,’ agreed Ingrid. ‘But the people of Norway know that when I’m wearing the blue cardigan, I want to be left alone. When I’m wearing a pretty dress and opening some building or another, then I’m there in my official capacity as a princess and they can give me flowers and ask for selfies and all those things.’

  ‘Good system,’ said Melanie.

  So, Ingrid, Friday and Melanie left through a back door of the palace and set out, walking straight down the driveway that led into Oslo’s main shopping boulevard. Amazingly, people did leave them alone. From the double takes of passers-by, clearly people did recognise Ingrid, but no one approached her. Whether that was the power of the blue cardigan, or Magnus glowering at everyone as he trailed close behind, Friday could not be sure.

  It was a beautiful day and there were crowds of people out – wandering about in the sunshine or sitting in outdoor cafes. The further the three girls got from the palace, the more they blended in and there were less heads snapping round to get a second look as they walked past.

  ‘Down here,’ said Ingrid, ducking into a side street. This was a less fancy neighbourhood. There was graffiti on doorframes, gum trodden into the bitumen sidewalk and weeds growing between the cracks of the gutters. But Ingrid had a huge smile on her face. ‘There it is!’

  Ingrid stopped outside a lurid pink and orange shop with a neon sign saying ‘Harald’s Vaffel’. Friday had not expected the waffle shop to look grungy.

  ‘Harald makes the best waffles, in the traditional Norwegian way,’ gushed Ingrid.

  ‘With ice cream?’ asked Melanie.

  ‘Well, you can get it like that, if you are a tourist who knows no better,’ said Ingrid. ‘But the authentic Norwegian way to eat a waffle is with jam, sour cream and brown cheese.’

  ‘You lost me at brown,’ said Melanie.

  ‘It is delicious, trust me,’ said Ingrid.

  ‘People in England eat cheese with fruit cake,’ said Friday. ‘The savoury and sweet flavours combined can be delightful.’

  ‘Yes, but cheese is not meant to be brown,’ said Melanie. ‘Not unless something is wrong with the cow.’

  They looked in through the window. There were polaroid photographs of all the menu items on the wall. The waffles did look good, but the brown cheese definitely looked brown.

  There was a squeal of tyres behind them. Friday didn’t think much of it – just someone taking the corner too fast. But then there was the screech of the car coming to a sudden halt, the acrid smell of burning brake pads and the slam of a door. Friday started to turn, but she was bumped from behind and over-balanced into the shop window.

  ‘There you are!’ exclaimed a man. ‘Quick! Get in!’

  When Friday righted herself, she looked up to see a big burly man had grabbed Ingrid by the shoulder.

  ‘I’m taking you to –’ continued the man, but that’s when a tornado of violence exploded. Magnus had lagged behind to give Ingrid some privacy. Now he rushed forward and leapt on the attacker. You don’t become bodyguard for the Crown Princess of Norway unless you’re good at your job. The attacker was handcuffed, footcuffed and tasered multiple times in less than ten seconds.

  ‘Stop, stop, stop,’ cried the attacker. ‘I’m with Interpol! I’m Agent Hans Olsen. I’m with Interpol!’

  Magnus paused before tasing him a fourth time.

  ‘My ID is in my pocket,’ said the attacker. ‘My chest pocket.’

  Ingrid reached into his jacket. She pulled out a leather-covered ID badge and inspected it. Friday peeked over her shoulder. It was legitimate. He was an Interpol agent.

  ‘Why are you attacking the princess?’ demanded Magnus.

  ‘I’m not,’ said the attacker. ‘I thought she was a girl called Friday Barnes. The palace told me I could find her here. I was told she was a short, brown-haired girl wearing a cardigan.’

  Friday and Ingrid looked at each other. They were about the same height and had a similar hair colour.

  ‘Why do you want her?’ asked Magnus. ‘Is she still a terrorist?’ He pulled Ingrid away from Friday just in case.

  ‘Hey! I was cleared of all charges,’ protested Friday.

  Magnus glowered some more.

  ‘Governor Offredi told me to find you,’ Agent Olsen explained to Friday. ‘We need your help. There has been a robbery at the Munch.’

  ‘The munch?’ asked Melanie. ‘Is that a restaurant?’

  ‘No, the Munch,’ said Friday. ‘It’s Oslo’s new Edvard Munch Museum. He’s the artist who painted The Scream – the ghostly expressionist portrait screaming on a bridge at sunset.’

  Melanie shook her head, ‘No, not ringing a bell.’

  ‘You know, The Scream,’ said Friday. She slapped her hands either side of her face and mimed horrified screaming.

  ‘Oh, that scream,’ said Melanie. ‘I’ve seen it on jigsaw puzzles.’

  ‘It expresses the way Edvard Munch felt when viewing the Norwegian sunset,’ said Ingrid. ‘It is the primal scream of nature.’

  Magnus was still glowering at Agent Olsen. ‘You just assaulted a royal princess,’ he accused.

  ‘I didn’t mean to,’ said Agent Olsen.

  ‘Yes,’ said Friday. ‘He meant to assault me. And I don’t mind. If there’s a problem at the museum I’d like to help.’

  ‘We need to check his credentials, to prove he is who he says he is,’ said Magnus.

  ‘There’s no time,’ said Agent Olsen. ‘The Munch is in lockdown. We can’t hold people indefinitely. We need to figure out what happened before we let people go.’

  ‘I can’t let you go with this man, your highness,’ Magnus told Ingrid. ‘It could be a trap.’

  Ingrid nodded. ‘I know, I am a princess, I must be sensible,’ she turned to Friday. ‘But you don’t have to be. Go with him. I’ll meet you back at the palace. I need to speak with my father anyway. We have things to discuss.’

  ‘Oh dear, no brown cheese and jam then,’ said Melanie. ‘What a shame.’

  ‘Don’t worry, Harald does takeaway packs,’ said Ingrid. ‘We can eat when you get back.’

  Friday got into the car with Agent Olsen, and was surprised when Melanie slid in next to her. ‘You don’t have to come, you know,’ Friday told her. ‘It may not be safe.’

  ‘Ingrid is buying brown cheese. I’m pretty sure I’ll be safer with you,’ said Melanie. ‘Besides, you need a wingman to watch your back.’

  ‘You’re going to fight off the bad guys for me?’ asked Friday.

  ‘Maybe not,’ said Melanie. ‘But I’ll scream to let you know when they’re coming.’

  ‘You’d probably be asleep and not notice they’re coming,’ said Friday.

  ‘Well you don’t want a stressful wingman,’ said Melanie.

  Agent Olsen pulled out into traffic and Friday set to work. ‘Take us through what happened.’

  ‘An hour ago, The Scream was taken off the wall,’ said Agent Olsen. ‘You’ve got to understand – the museum is brand new. It has the very latest technology.’

  ‘I’m not surprised, after the 2004 robbery,’ said Friday.

  ‘What happened?’ asked Melanie.

  ‘The old Munch Museum was robbed by a heavily armed gang,’ explained Friday.

  ‘It was terrible,’ agreed Agent Olsen. ‘No one wanted that to happen again, so the new Munch was built with the highest level of security. All the glass is bullet-proof. No one can bring any personal items inside. Everyone has to pass through metal detectors. The Scream in particular is monitored with state-of-the-art electronic surveillance. There was a sensor in the frame. As soon as it came off the wall, the entire museum went into lockdown. Literally, the external doors all locked. No one could get in or out.’

  ‘So the painting and the thief are still in the gallery,’ said Friday.

  ‘Yes,’ said Agent Olsen. ‘At least we assume so, but we can’t find them. The police have interviewed staff and visitors. They have thoroughly searched the building. But they’ve found nothing.’

  ‘Wasn’t there video surveillance?’ asked Friday.

  ‘Yes,’ said the guard, ‘but the cameras in The Scream’s room were disabled.’

  ‘How?’ asked Friday.

  ‘We don’t know,’ said the guard. ‘The cameras are ten feet off the ground.’

  ‘That’s the first mystery, then,’ said Friday.

  ‘We can’t hold people much longer,’ said Agent Olsen. ‘Some of the visitors have started talking about their “human rights”. The staff aren’t happy about being detained either. They’ve contacted their union and the union rep is outside, complaining that he can’t come in to help them complain.’

  ‘The irony,’ said Melanie.

  ‘On top of all that,’ continued Agent Olsen. ‘Among the visitors is a large group of senior citizens from a care home. They need to get back, because they need to take their regular scheduled medications.’

  ‘So there’s a ticking clock,’ observed Friday.

  The Munch was right on the harbour, so it only took Agent Olsen a few minutes to get there from the central shopping district. It was a huge museum built on an old dock. The building had been designed in the latest style of avant-garde architecture. As a result, it looked more like a terrifying giant air-conditioning vent than a building that humans would inhabit.

  ‘Did the architect want to scream too?’ asked Melanie as they pulled up outside. ‘It’s a very angry-looking building.’