The sky was starting to darken. Max checked her watch. It was really time to be getting back to the train station.

For the first time since she had set out into the bright Budapest day, the knot in her stomach started to retie itself. This wasn’t Paris. The streets were strange and unfamiliar, and there was no one who would understand her if she asked for directions, and she didn’t know where you could go to find out information or get a map. If Ester and Klaus had left before her, what was she going to do?

Five minutes later, they still hadn’t appeared, and hot tears were pricking at Max’s eyes. She checked her watch again, even though she knew what time it was: late. Almost too late. They must have already left. She tried to ask a passing woman where the train station was, but the woman couldn’t understand her, and when Max started miming a train, complete with desperate chugging noises, she hurried off in alarm.

“What are you doing?” said a voice behind Max – in sweet, glorious French. Max spun round to find Celeste watching her, eyebrows raised.

“Oh!” cried Max, breathless with relief. “Hi! I’m lost. You’re going to the train station, right? Can I come with you?”

Celeste didn’t answer, but she began walking down the path, and seemed to expect Max to follow. So Max hurried after her.

“What are you doing here?” Celeste asked, without looking round.

Once again, Max seemed to have angered her, although she couldn’t think why. “Um. Swimming.”

“Without your guardian? And without knowing how to get back to the station?”

“Um,” said Max, “I thought I knew. But I got confused.” “You seem to be quite careless,” said Celeste. She made it sound as if Max’s carelessness was a crime against her personally. Or, maybe, as if she didn’t believe it was carelessness.

“Sorry,” said Max.

There was silence all the way to the edge of the park.

“I’m Max,” said Max.

“OK,” said Celeste. She did not offer her name, so Max had to go on pretending not to know it.

“I’m going to Istanbul,” Max added, “to visit my great-aunt.” (Which was true enough, but seemed like a very distant idea now – Max couldn’t imagine arriving at the other end, and being polite and making small talk over dinner and so on.)

Celeste didn’t even bother with an “OK” to that, so Max gave in. She was too tired to worry much about investigating Celeste. She was their least likely suspect anyway, Marguerite had said; and Max’s head was as full as she could manage already.

As they walked, Budapest continued to darken around them, and the street lamps were turned on. Celeste kept up a furiously fast pace, and Max had to half run to keep up.