Collis looked at Wang-Pu uneasily. But Wang-Pu simply continued to smile, and set out the saucer on the table. He poured a little of the dark liquid into it, and then took up one of the baby mice by the tail, and dipped it into the liquid as if he were coating a quenelle with egg yolk.

‘This is soya sauce,’ explained Wang-Pu. ‘It isn’t medicinally necessary, but it gives the mouse some flavour.’

‘Flavour?’ asked Collis in disbelief; but before he could say anything else, Wang-Pu had tipped back his head, raised the squirming mouse to his open mouth, and dropped it down his throat. The Chinaman gave a hefty swallow, and the little creature was evidently gone.

Collis, alarmed said, ‘I don’t really see what benefit that’s supposed to afford you.’

Wang-Pu shrugged. ‘The mouse bursts inside the stomach, and its warm blood bathes the ulcer. That is the theory, in any event.’

Collis waited for the Chinaman to say something else, but he didn’t. Wang-Pu simple took another sip of whisky, put away his medicine case, and sat back to watch the shores of Solana pass them by, a dry-baked, desolate land, where birds turned and drifted like leaves on a still summer pond.

Collis was dozing in his chair as the steamer docked at Sacramento. It was early evening. He opened his eyes to see a tree-lined riverbank, and beyond, through a hallucinatory ripple of heat, a small town of flat-fronted houses and stores and saloons, neatly laid out in squares. The wood and adobe walls of the buildings were lit by sinking sunlight under a sky that was still stunningly blue. In the far distance, beyond the squarish outlines of the state capitol building and the cluttered rooftops downtown, across a wide purplish wilderness of trees and empty land, Collis could see the far, entrancing peaks of the Sierra Nevada. He straightened his hat, brushed his sleeves, and then stood up and went to the steamer’s rail.

There were several steamers and small cutters docked along the river’s edge, and the water was clustered with lighters taking goods and passengers ashore from the ships anchored out in midstream. Their oars dipped into the sun-gilded river and made criss-cross patterns of dazzling light.

Charles came up from astern, his face redder than usual, and hooked his thumbs into his vest. ‘Well, Collis,’ he said, ‘I’ve brought you home, then.’

Collis nodded. There was a smell of dust and chaparral on the breeze. By the river’s edge, a congregation of carts and Conestoga wagons had collected, and a group of men in plaid shirts and blue work pants were smoking pipes and watching the steamer tie up. On the foredeck, a man with a high, hoarse voice was playing the accordion, and singing, ‘Oh, I remember well, the lies they used to tell, of gold so bright it hurt the sight, and made the miners yell.’