Luigi looked up at the rock and whistled. ‘Quella era una cosa pazzesca da fare,’ he said.

‘Pazzo,’ Mauro repeated and tapped his finger on the side of his head. ‘Crazy.’

James shrugged. He was sure that from now on he and Mauro would be friends. Which was a relief, as he knew that he would be too scared to ever try a stunt like that again.

He waded towards the two boys, grinning happily, but suddenly yelled and fell sideways in the water. It felt as if a nail had been driven into his foot.

Mauro and Luigi hurried over, picked James up and dragged him ashore. They looked at his foot. Several broken black spines were sticking out of his heel.

He’d trodden on a sea urchin.

There was a terrible burning sensation as the poison, still pumping from its broken spines, soaked into his flesh.

The two Sardinian boys shouted excitedly in Italian and crowded round him. Luigi put out a hand to prod at the spines but Mauro pushed him away angrily and the two of them argued. Finally Mauro indicated to his friend to stay back and looked at James.

‘OK?’ he said.

‘Not OK,’ said James and he bit his lip. The pain was awful. His whole foot was throbbing and the poison was already spreading from his heel up into his ankle.

Mauro studied his foot carefully, before delicately plucking the spines out one by one. But they were so brittle that the barbed ends stayed stuck in, and, as they were disturbed, the poison sacks at their tips discharged more of their agonising cargo.

James winced and tried not to make any sound, but it was difficult. At last Mauro was done. He looked at James, his face concerned.

‘Come,’ he said and helped James up.

James put his arms round the boys’ shoulders and they struggled with him up the steps to the villa. Once there Mauro left James on the terrace and busied himself in the kitchen before returning with two bowls and a sponge. He carefully washed James’s foot with vinegar from one bowl before plunging it into the other, which was full of very hot water. The pain slowly dimmed to a dull ache and a pulsing sensation and James was relieved that the worst of it was over.

Mauro studied James’s heel. It was still studded with the broken ends of the spines.

‘OK?’ said Mauro.

‘OK,’ said James.

Mauro once again talked to Luigi, who looked sceptical, and soon another argument flared up, but once again Mauro won.

‘Is OK,’ he said, then he picked up a large smooth stone. ‘OK,’ he repeated, which made James think that it really wasn’t OK at all.

Mauro knocked the stone against his chest and nodded. ‘I know,’ he said. ‘Is OK.’