It did fetch them, both of the grown-ups. We heard their hasty tread behind us and heard the window being raised and shut. A catch clicked. We got up, then stood, the three of us, side by side, and Wim, taking a penknife from his pocket, as if he had rehearsed this, reached up with it and made as if to insert the blade between the top of the sash and the architrave. The two people inside—they had retreated to the far side of the room behind the table—stared at us in horror. They were clinging to each other, not in a graceful embrace, but each clutching at the other’s clothes, the woman’s hands making frenzied grabs at the man’s chest and shoulders. Her face was such a mask of pain and terror, her eyes huge, her mouth half-open, that I resolved in that moment I’d never again take part in a hunt for anyone or anything. Then she let out a loud scream.

We didn’t move, beyond Wim withdrawing his hand from the window and putting the penknife back in his pocket. The scream had awakened the child and the sound he made equaled hers. We stood our ground. We had to if this was going to work. Her screams changed to cries of “I’m coming, it’s all right, Mummy’s coming” on sobs of terror, and she ran from the room. He followed her, slamming the door behind him. I thought I heard a key turn in the lock of that door.

“There’s no phone in the room,” Silver whispered. “It must be somewhere else in the flat.”

I shivered. “She called herself ‘Mummy,’ did you notice?”

“Of course she would, of course she’d do that.”

We ran back along the balcony this time and climbed onto the roof. Wim said it was the safest place to be, but I thought that up there would be the first place the police would look. If there were any police. I thought of that evening a week before when the fire engines had come, their sirens blaring, and waited for that sound again. This time it would be from police cars. What Wim had done I rather disliked, not so much the smoking out of the occupants of 4E but his act at the window, the penknife inserted between wood and glass, as if he meant to break in and enter. I watched him as we waited, his inscrutable sallow face, the yellow-green eyes like those of a big cat. It was then I noticed for the first time how strange his hands were, the fingers disproportionately long, the backs short and narrow and the wrists as fine, symmetrical, and honed as machine parts.