‘I can’t go on,’ she said. ‘Can’t we just wait here?’

‘No,’ said James. ‘We need shelter.’

‘Can you hear that?’ said Amy.

‘What?’

‘It sounded like horses’ hoofs. Maybe Zoltan’s coming back.’

James strained to listen. He hadn’t imagined the sound after all. He looked around to try and see where it was coming from.

Then Amy stood up and grabbed his arm.

‘James, look,’ she said.

Through the heat haze he could see the dancing shape of a horse and rider walking slowly towards them.

He squinted. Now he knew he had sunstroke. The rider appeared to have on the ceremonial outfit from the carnival, with the deathly white woman’s mask.

And he held a silver sword at his side.

The horse broke into a trot, then it started to canter, then it was galloping at full speed, and James realised that it was headed straight for them.

The rider raised his sword, the point aimed at James’s heart. James backed away. There was nowhere to run out here in the open, nowhere to hide.

He stood his ground, eyes fixed on the sword. The rider’s eyes were hidden behind the mask. The horse’s hoofs pounded on the hard ground. The air was hot and still. James waited until the horse was almost upon him and then threw himself to the side. The point of the blade swished harmlessly by and James was aware of a blur of flashing hoofs.

He rolled on to his feet and saw that the horse was wheeling round for a return attack, but it hadn’t gone far enough to pick up much speed and as it came back James dodged across in front of it so that he was on the opposite side to the rider’s sword arm.

But then the rider turned and switched his attack to Amy. She stood there not sure what to do as the horse bore down on her. However, at the last moment, she scooped up a pile of powdery dirt and threw it into the air, startling the horse, which shied away.

James knew they couldn’t keep this up for much longer.

The rider galloped away and calmed his horse, then began to circle them, planning his next move.

‘Split up,’ said James. ‘I’ll try and get him to come after me. You see if you can get to the woods.’

‘No,’ said Amy. ‘We’re in this together.’

James saw movement off to the side and looked over, amazed, as two more horses burst out of the trees.

It was Zoltan and Tree-Trunk, the big Samoan in the lead, his harpoon held up like a spear, a fat cigar clamped between his teeth.

The rider in the mask dug his heels into his horse and charged at them.

Tree-Trunk was well ahead of Zoltan, heading straight for the other horseman.