They all met at Oslo airport the following morning. Binky was in his army fatigues and carrying his duffel bag, ready to return to his post. Friday and Ingrid waited with Melanie. They had to hang on to her – she didn’t like early starts. If they took their eyes off her for a moment, Melanie would find somewhere to lie down and go back to sleep, which wasn’t safe in the sub-zero temperature. Magnus hung back, glowering as usual, while Dr Finsberg sulked as far away from the group as possible.

‘Here comes the minister,’ said Ingrid.

A stretch limousine drove through the security checkpoint and glided to a halt next to the hangar. The car had two little Spanish flags fluttering above the headlights. Ian was the first to get out, then he stood back and held the door open for Cassandra. She emerged with the elegance of a cheetah – a cheetah that was too relaxed to kill you, but might think about doing it later. Her father was more portly and made a less picturesque exit. Ingrid went over to formally greet them. Ian walked across to talk to Friday.

‘Nice coat,’ he said, smirking wryly. Friday was wearing Ingrid’s clothes again. It was a huge coat suitable for extreme weather conditions, but it was still more elegant than anything Friday owned herself.

‘Why are you here?’ Friday asked.

‘To tour the Seed Vault,’ said Ian.

‘Since when have you been interested in seeds?’ asked Friday.

‘Since they were stored on a remote arctic island,’ said Ian. ‘I might get to see a polar bear.’

‘I hope not,’ said Melanie, sleepily. ‘I don’t want to have to run anywhere.’

‘Have you seen the paper this morning?’ Ian asked Friday.

‘No,’ said Friday. ‘Why?’

‘There was a lovely photo of you,’ said Ian.

‘Again?’ asked Melanie. This woke her up a bit.

‘Yes, you do seem to be popping up in print a lot lately,’ said Ian.

Friday blushed. She had hoped Ian hadn’t seen the photo of her and Binky.

‘May I see?’ asked Friday.

Ian handed her the paper. It was already folded to the relevant page. There was a big colour photograph of her dancing with Arthur. Her bright red strapless dress looked stunning in contrast with his black tuxedo, but it was the look on her face that made the picture stand out. Friday remembered the exact moment. She had looked up at Arthur in wide-eyed wonder because she couldn’t believe she was actually dancing. But that’s not what it looked like here on the page. She looked like a love-struck girl in a passionate embrace.

‘You’re very photogenic these days,’ said Ian.

‘Shut up,’ said Friday. She was too mortified to construct a more complex sentence.

The headline read ‘Danish Prince Finds Love with Mystery Vixen’. There was a reprint of the photo of her and Binky below, so that readers would know she was the same girl.

‘Vixen?’ said Friday.

‘That’s so cool,’ said Melanie.

‘Do you think it’s a reindeer reference?’ asked Ian. ‘You know – Dasher, Dancer, Prancer, Vixen?’

Friday elbowed him in the ribs.

Ingrid was still talking to Minister Mendoza, but Cassandra came over to join them.

‘Did you meet Cassandra last night?’ asked Ian.

‘No,’ said Friday.

‘No, I suppose you were too busy,’ said Ian. ‘Cassandra, come and meet my friends from school. This is Friday and Melanie.’

‘Delighted,’ said Cassandra.

‘Wainscott!’ Binky called over from by the small plane. ‘Help me load the bags on the plane.’

‘Sure,’ said Ian.

‘Magnus isn’t allowed to help,’ Binky explained loudly, pointing to Magnus in case anyone didn’t know who he was talking about. ‘He needs to keep his hands free in case Ingrid is attacked by an assassin.’

Magnus glowered extra especially hard at Binky as Ian jogged over to help, leaving the three girls together.

‘So, you’re Ian’s girlfriend?’ Melanie asked Cassandra casually.

Friday closed her eyes. She wanted the ground to open up so she could sink into a pit of magma rather than listen to this conversation.

‘Yes,’ said Cassandra. ‘We met at the Bilbao. There was a cocktail party. We were the only two people under the age of forty there.’

Melanie squinted at Cassandra. ‘I can tell you’re lying.’

‘Melanie!’ said Friday, her eyes flying open. ‘Even I am not that rude!’

‘But I’m not sure which part she’s lying about,’ said Melanie, tilting her head as if this would help her read Cassandra’s mind.

‘I can assure you I did attend the party,’ said Cassandra. ‘I was wearing my blue Armani. There were photos in the social pages.’

‘Okay, you’re not lying about that,’ said Melanie. ‘So the lie must be – that you’re Ian’s girlfriend! You don’t care for him at all.’

Cassandra glanced over her shoulder at Ian. ‘Shhh. Don’t say that. You’ll upset him. I am very fond of Ian.’

Melanie nodded and interpreted for Friday, ‘She’s telling the truth now,’ before turning back to Cassandra. ‘So, what’s the problem? You’re not attracted to stunning, gorgeous, intelligent, tall blond men?’

‘Melanie, think what you’re asking,’ said Friday. ‘It’s none of your business.’

‘He’s lovely,’ said Cassandra. ‘But he’s not in my league. Besides, I don’t have time for boyfriends. I’m trying to focus on my studies.’

‘You are?’ said Friday.

‘Why are you surprised?’ asked Melanie. ‘Did you assume because Cassandra is staggeringly beautiful that she wouldn’t be academically inclined?’

‘Yes,’ admitted Friday. ‘But I suppose that is stupid. My brothers and sisters all look like they walked out of a photo shoot for a fashion magazine and they never think of anything other than physics, or proving other physicists are wrong.’

‘He’s my cover,’ said Cassandra. ‘Daddy wants me to be a diplomat. It’s all parties and networking. It’s such a bore. I’m trying to get in to Université Paris Science et Lettres. They have the best mathematics course in Europe. He can’t stop me if I get a place there.’

‘But Ian’s smart,’ said Melanie.

‘Do you think? I suppose, in some ways, yes,’ said Cassandra. ‘He’s good at high-school math. But he doesn’t know anything about tertiary-level pure mathematics.’

‘I like her,’ said Friday, smiling at Cassandra. ‘I like the way she thinks.’

Melanie just rolled her eyes.