Domnicus gave it first to the emperor who took a sip and passed back the cup then bowed his head. After him, Lilla and then Gerutha, and then it was his turn, and he was tipping the cup back, straining against something in him that wanted to smash it on the floor.

Too late, he saw the purple fire flickering on the surface of the liquid in the bottom of the cup, too late it rushed into his open mouth, too late he swallowed down the liquid fire, feeling it pour into his body. . .

Lilla had watched him take the cup, curious at what had come over him. But then in the next moment, he dashed the cup from his hands, flung himself backwards and started choking on the floor. It was shocking, startling, but immediately she was on her knees beside him. ‘Help him,’ she begged. ‘He’s choking! Help him!’

His eyes were wide and staring as he clawed at his own throat and then, with horribly slow deliberation, they rolled back in his skull. All of them apart from her stood frozen in shock. She managed to pull him onto his side but as she did a thick jet of vomit suddenly spewed from his throat in a foul, glutinous gush across the stones.

‘What’s happening?’ she cried. Domnicus was the first to respond. He was next to her. Erlan’s body was convulsing violently, his skull thudding against the stone. ‘Put something under his head, quickly,’ ordered the priest. Then Gerutha was there, her shawl scrunched into a ball – she tried to wind it around his thrashing head but his movements were too violent. ‘Hold him. Hold him!’

Einar was on his knees, his big fists pressing down on his friend, locking his shoulders against the floor to stop him doing himself worse harm. Then Erlan’s mouth opened, so wide he looked like a snake dislocating its jaw. It was obscene. And suddenly a voice shrieked from inside him, filled with such rage and pain. A voice, yes, but not his own. It was something inhuman, something evil. Erlan’s arm broke free, he seized Einar by the collar and flung him away as though he was made of goose down.

‘Get the cross,’ Domnicus instructed Gerutha. ‘There! The one on the altar.’ Gerutha ran to fetch it. ‘There’s a demon in him, I think. I’ve seen this before. Not many times but. . . do not loosen your grip on him. He will harm us and himself if not restrained.’

The emperor stood above them, peering over. ‘Can you help him?’

‘Maybe. Hold him, I said,’ Domnicus snapped angrily at Einar who had crawled back into position.

‘You bloody hold him, priest – he’s too strong for me. Just what the hell is going on?’

‘Prayer drives it out,’ Domnicus gasped, pushing down on his chest.

‘Drives what out? What’s in him?’

‘An evil spirit has its hold in him.’