They did as Kate instructed until Natasha installed herself in one corner of Șark Kahvesi, a coffee shop with patterned tablecloths and garish wallpaper close to the market entrance. The place was full of old men reading their morning newspapers beneath a couple of wooden ceiling fans.

Kate led Julie direct to the table.

‘I ordered you Turkish coffee and some baklava,’ Natasha said. ‘I hope you’re hungry.’

It was only when they sat down that Kate took in just how attractive Natasha Demidova was. She had a fine nose, Slavic cheekbones, long eyelashes and flawless skin. Her face lit up when she smiled.

‘I thought your surveillance was so amateur, you must be Italian or French,’ the Russian said. ‘But then I thought, Ah, no, two British intelligence officers, but on their own. Correct?’

‘It was a pretty pointless game. I’ve never seen anyone in tennis whites try to lose themselves in a crowd.’

‘Then how limited your experience has been. I can lose myself wherever, whenever and however I wish to.’

Kate bit her lip. Julie nudged her underneath the table.

‘You are from British intelligence, I assume?’ Natasha said. ‘I’ve been waiting for you.’

‘We’re from a special unit set up to investigate the information you passed to Tess Winkelman. That’s why we don’t have back-up.’

‘Just the two of you?’

‘More or less.’

‘I can see how seriously you are taking this.’

Kate couldn’t stop herself bridling. ‘We’re taking your observations on security very seriously, which is why the unit is small and has travelled here without support.’

Natasha lit a cigarette and pushed the packet across towards them. Julie took one, but Kate restrained herself. The Russian rested her perfectly formed elbows on the table. ‘You don’t need me to tell you that Istanbul is crawling with every foreign intelligence agency on the planet, most of which know me well. So, whatever you want, get on with it.’

‘We’re trying to establish why you would share such secrets with a total stranger,’ Kate said.

‘Because they killed my lover. And I adored him.’

Kate felt the blood rush to her face and was only saved by the arrival of Turkish coffee and enough baklava to feed an army.

‘And,’ Natasha continued, ‘I knew that a play-it-by-the-book diplomat like Tess Winkelman would do exactly as I asked and take the information straight to your prime minister.’

Kate stared at her coffee, stirring it carefully. She hadn’t expected Sergei’s lover to be quite so alluring in the flesh. ‘How do you know they killed him?’ she asked.

Natasha fixed Kate with a steady gaze. ‘Trust me, he was as fit as a stallion. There is no possibility on God’s earth that he died suddenly of a heart attack.’

Kate wondered if Natasha knew what had really happened that night on the train from St Petersburg to Moscow. Was she aware that Kate had been with Sergei moments before his death?

‘We’d be grateful,’ Julie said, filling the silence, ‘if you could tell us everything you know.’