‘I will shoot,’ the woman said, and Casey believed her.

The woman walked forward, down the wide steps. A few paces away from the sundial, she stopped.

‘Go into the house.’ An order. ‘Walk slowly.’

There was nothing else to do.

‘All right.’

Casey began to move towards the building. The woman watched her, the rifle moving smoothly with Casey.

As she passed the woman, Casey glanced across. That golden shimmer . . .

‘Keep going.’ A voice like ice.

Casey walked up the wide limestone steps, through the oak door, into the brightness of the hall.

‘On your left.’

The hall was baronial, a grand staircase sweeping away, and a vast carved fireplace dominating the space. A deer’s head stared blankly above. Two huge bloodhounds sprawled beneath. As Casey crossed the hall, one of them looked up, yawning and stretching.

At the threshold of the drawing room, Casey hesitated.

‘Do sit down,’ behind her, the woman said mockingly.

Casey sat down on a huge white sofa. Straightening her shoulders, she looked at the woman.

‘Good evening, Mrs Greystone.’

The woman smiled. ‘Welcome to Tawton Court.’

They contemplated each other for a moment. A fire burned in the hearth, sending shadows dancing round the room.

‘Phone,’ said Clio, and as Casey handed it over, ‘are you recording this?’

‘No,’ said Casey. Clio’s eyes raked her. She stood, picked up Casey’s satchel and slung it on the fire. Casey’s eyes followed it, and then hardened on Clio.

‘They know I am here,’ said Casey. ‘The Post knows.’

‘Maybe,’ Clio Greystone said thoughtfully. She folded herself into a white armchair.

Clio looked the same, and yet she was almost unrecognisable. The superficial glamour had been stripped away, along with the pretty dress, the studded boots, the Balenciaga bag. Clio wore a simple dark top and black cropped trousers. This woman enjoyed dropping the camouflage, Casey thought. She revelled in the act first, and then smirked in the mirror as she stripped off the layers.

The gun pointed squarely at Casey.

‘I know what you’ve done,’ said Casey.

‘I should have guessed,’ Clio almost smiled, ‘when I found myself reading an article about a tennis match, of all things. It was clever, that. Arachne and Aceso and Portunus. And I suppose you’ll find the rest, in the end.’

A nice little trophy, Casey thought, raging inside. She stayed silent.

‘But then you triggered an alarm as soon as you stepped on the drive,’ said Clio. ‘I imagine you expected something like that.’

Open gilded gates.

‘Maybe.’ Casey waited. ‘You need to let Dominic Burton-Smith go, Clio. My colleagues will call the police. Please.’

‘You have been busy.’ Clio ignored her. ‘Blackmailing William Cavendish. Running off to Dhaka. Searching that ship. You’ve been very persistent, Casey.’

A closed terrarium sat on the table beside Casey. Casey gazed at it now, at the cut glass, the moss, the delicate ferns. An elegantly perfect ecosystem, in its own discrete world.