But it was a risk she had to take.

She entered the British Museum at ten o’clock, brandishing a Japanese language guidebook to London she’d bought at Narita airport. She wandered round a few rooms full of ancient statues. A memory surfaced of walking round the same rooms with Hiko, but the memory felt so distant it could have belonged to someone else, not Wada as she was now. She went to the café specified by Caldwell – not the main one, in the Great Court, but the small Montague Café near the museum’s rear entrance. There she sat sipping green tea and leafing conspicuously through her book. No one paid her the smallest amount of attention. This was reassuring in its way. She’d always been someone others found easy to disregard. And, just now, being disregarded was what she preferred to be.

She kept an eye out for a solitary middle-aged Englishman matching her mental picture of Martin Caldwell as ten thirty came and went and became ten forty.

No solitary middle-aged men of any nationality came in. No one glanced meaningfully in her direction. She checked her phone, to see if Caldwell had sent her a message saying he’d be late. He hadn’t. She sent him a message of her own. Where are you? There was no reply.

And there was no Caldwell.

She’d flown thousands of miles to meet this man. To learn what he knew about Peter Evans and the death of Shitaro Masafumi.

But she wasn’t going to meet him. Not here. Not now. By eleven o’clock, she knew, though she stayed another half an hour. He wasn’t coming.

There was still no message.

She walked out into the courtyard at the front of the museum, turning over in her mind all the contingent possibilities at play. Kodaka was dead. Was Caldwell dead too? Everything seemed and felt normal, this spring morning in London. Pigeons. Tourists. Red buses. Grey clouds.

But something wasn’t normal. Something had happened. And might still be happening. Beyond her grasp. Out of her control. The file was going to take at least a couple of days to reach her. Until then, she knew nothing. She was helpless. And quite possibly in danger as well.

Think, she told herself. Reason it through. It was what her father had often told her to do with a troublesome piece of school homework. He’d tap the side of her head and say, ‘You have a brain in there. Use it.’

She pulled her shoulders back and strode out through the gates into Great Russell Street. She was alone. She was vulnerable. But she wasn’t resourceless.

And she wasn’t giving up.

SIX