“I’m glad you took a look, mon lapin,” said Marguerite. “It was stupidly dangerous, but since you pulled it off, I’m glad.” She knitted her fingers together and rested her chin on them thoughtfully. “Celeste’s probably just in the wrong place at the wrong time – although the note is strange, I agree. I’ll keep her in mind. But we can’t tail all of them. Let’s stick to Rupert and Ester: they’ve got history.”

Max stared at her. “We’re following people?”

“I was hoping so. I badly need some more information before we arrive at Istanbul.” She did her best to look earnestly at Max without losing sight of the road. “Will you help me? It’s up to you. I promise you can trust me, mon lapin.”

Max looked out at Budapest, flooded with wintry light, and felt like she could go anywhere and do anything. “Yes,” she said, “I’ll help.”

“Excellent,” cried Sister Marguerite, pounding the table. She grinned. “Then you follow Ester Rosenkrantz. I’ll take Rupert Nobes. Try and stay out of sight when you can, but don’t let her lose you.” She reached into her habit and put some more forint notes on the table. “Take these in case you need to pay to get in anywhere. Stick to her – you never know when she might reveal something crucial. And scribble down anything interesting she does in that notebook of yours.”

Max folded up the forints and put them in her coat pocket. Suddenly, Sister Marguerite sat bolt upright and grabbed her arm. “Ester and Klaus!” she hissed.

Sure enough, the pair had appeared between the cream pillars. Max could tell that Ester was talking, because pigeons were taking off left and right in alarm.

“There’s your mark! Go, go, go!” said Marguerite, flapping her hands about in high excitement. Max hurried to her feet, untangling all her scarves from the chair and grabbing her case. She had a hundred more questions – some of them important ones, like, “If I lose them, how will I find my way back?” – but there was no time. She hurried to the door.

“Oh, and Max—”

“Yes?”

Sister Marguerite was still watching the road like a hawk. Or, thought Max, a sillier, stringier bird – an ostrich, maybe. But even if she was silly, she had turned out to be a friend after all – a friend and a detective and an adventure all rolled into one.

The nun gave her a thumbs up, without turning round. “Good luck.”

6. Marek, Marek and Ruszy