They headed wearily up the long incline back to the lock-up. Septimus had been so impressed with Marcellus’s insistence on safety that—even though he knew Marcellus did not like to talk about it—he said, “I just don’t understand how the Great Alchemie Disaster ever happened.”

Marcellus sighed. “That, Septimus, makes two of us. I don’t understand either. It makes no more sense to me now than it did all those hundreds of years ago. But what I do know is that if the ExtraOrdinary Wizard had not intervened in such a high-handed manner—excuse me, Septimus, it rankles to this day—and closed down the Fyre, then many lives would have been saved. And my house in Snake Slipway would not be so perishing cold every Big Freeze.” Marcellus smiled at Septimus’s bemused expression. “The Ice Tunnels were not just the old communication tunnels between the ancient Castle buildings; many of them were also part of the Castle heating system. As you know, they run beneath every old house. The hot water from the Fyre kept us all warm. People loved the Fyre in those days.”

“Ah,” said Septimus, thinking that that made a lot of sense.

Evening was falling when they emerged from the lock-up. They hurried off to Alchemie Circus, where Lucy had been anxiously awaiting the first plume of smoke to appear from the chimney. She ran excitedly toward them.

“It’s working—look!” Lucy pointed up to the thin wraith of white smoke that was climbing lazily up into the evening sky.

“Well done, Lu,” said Simon. “It’s a brilliant chimney.”

“Thanks, Si,” said Lucy.

“Yes,” said Marcellus. “It’s very nice. Very nice indeed.”

People had been hanging around Alchemie Circus all day, waiting for the first breath of smoke to emerge from the chimney, but with the onset of dusk, most had drifted away. But although the Living had got bored and gone home for supper, Alchemie Circus was, in fact, still packed—with ghosts. They had come to see what many considered to be the very heart of the Castle come alive once more. Most approved, but there were some who did not. These were the ghosts who had been present at the Great Alchemie Disaster. Indeed there were some there who had entered ghosthood because of the disaster. Some had been burnt to death by the hundreds of subsidiary fires that had swept through the Venting system and burst, unannounced, up through the floors of houses. Others—like Eldred and Alfred Stone—had been frozen into the Ice Tunnels during the panic to Freeze them. But those who had lived before the disaster had good memories of the Fyre. It had been the beating heart of the Castle, and those who had known life with it considered the present-day, Fyre-free Castle to be a poorer place.

But nothing stayed secret in the Castle for long and word soon spread that the Fyre was lit. Later that evening, after Septimus had gone back to the Palace for Sarah’s last-night-of-the-holiday supper, Marcellus, Simon and Lucy joined the edgy crowd at the foot of the chimney, many of whom were clutching the recently reissued All You Need To Know About The Great Alchemie Disaster pamphlet.

“Oi!” someone called out. “It’s the Alchemist fellow.”

A young woman carrying a toddler waved the pamphlet angrily. “Have you read this?” she demanded.

“Madam, I wrote it,” said Marcellus.

“Rubbish!” yelled a bookish, elderly man wearing a fine pair of gold-rimmed glasses.

“Well, I’m sorry you didn’t enjoy it. I did my best.”

“I meant there is no way you wrote this. You Alchemists!” the man spat out the word in disgust. He waved his copy of the pamphlet under Marcellus’s nose. Marcellus caught a waft of old paper—it was one of the original ones. “You Alchemists always covered everything up. And you, Mr. Pye, were one of the worst offenders.”

Marcellus held his hand up in protest. “I am sorry,” he said. “Please believe me, the Great Alchemie Disaster was not of our making.”

“So whose fault was it, then?” demanded a teenage boy. “The tooth fairy’s?” The crowd giggled.

Marcellus had known that the return of the Fyre to the Castle would not be popular. He had given the problem a lot of thought and he hoped he had a solution. He raised his voice above the murmurings of discontent. “To prove to you that we have nothing to hide, we will be starting guided tours of the Great Chamber of Alchemie.”

There was a stunned silence.

“All will be welcome and it will be my pleasure to meet you at the UnderFlow Quay and show you around personally. You may book the tours with Rupert Gringe at the Boathouse. I look forward to seeing you all again shortly.” With that Marcellus bowed and strode away.