‘Your children are safe. Come with us and they will not be harmed.’ The men spoke Russian, of course. She cursed her complacency.

‘Come where?’

‘Do as you are told.’

‘I need to tell—’

‘No! Don’t be foolish,’ the man told her. ‘It is not worth the risk.’

They ushered her out of the side door of the church and hurried her along the smooth cobblestones of Campo de la Guerra. It was a relatively wide street that led down to the canal, lined with pastel-coloured houses, shops and cafés. It was quiet by the standards of central Venice, but there were enough people for her to make a scene if she wished to. Kate glanced over her shoulder. The men had slipped their Brownings into their pockets.

At the end, she was forced into a launch. She turned to face them. ‘Where are you taking me?’

‘Save your voice,’ the acne-scarred man told her.

‘My children will wonder what’s happened to me.’

‘They’re safe with your husband.’

‘Is this his doing?’

The man motioned for her to sit. She refused. The launch set off gently, motoring deeper into the heart of the city in all its rambling, faded glory, the buildings around her a patchwork of peeling paint, plasterwork and exposed brick. As they crossed under the first wrought-iron footbridge, a group of Chinese children watched her pass.

The canal swung to the right, opening out to the baroque splendour of the church of Santa Maria della Fava, with its ochre bridge and peaceful square, full now of tourists sheltering from the city’s busier thoroughfares.

Just beyond the church, the launch swung right again and immediately glided to a halt by a villa, with stone steps that stretched down to the water’s edge. A young man in a smart white uniform was waiting for her. He offered his hand. She did not take it. ‘Please follow me, Mrs Henderson.’

He led her through a cool, damp, spartan lobby, which looked as if it flooded when the tide was high, and up another set of stone steps to a richly furnished hall. A chaise longue upholstered in burgundy velvet lined one wall beneath what looked like a Picasso. A coffee-table stood alongside what looked like a solid gold Buddha the size of a small horse.

She followed the man up to a sitting room on the floor above, where the furnishings were lighter, to fit with the sun streaming in from full-length windows opened to the balcony. ‘Please wait here,’ the man said.

Kate stepped outside. It was very bright now, the sun warm on her face, the palms and bougainvillaea in pots curling over the lip of the iron railings. She returned to the room and walked around it, assessing the art that graced its expensive walls: a Monet certainly, another Picasso probably – no, for sure, now she looked closer – a Cézanne, Van Gogh’s self-portrait with a bandaged ear.

‘You have an eye for a master?’

Kate swung around. Mikhail Borodin stood in the doorway, six feet two of tanned, lean muscle. ‘I have an eye for value. The paintings in this room must be worth two hundred million or more.’