The Darke Domaine stopped at the Ramblings.

It had faded slowly. First they began to hear the sound of Thunder's hooves, muffled and distant but growing louder every step. Hazy shadows began to form recognizable shapes - Lucy first heard, then saw Marcellus's mangled shoe flapping on the paving stones - but they knew they had reached the boundary when they could at last make out the glimmer of a distant rushlight. As they stepped out of the Darke Fog, they found themselves in an alleyway not far from Ma Custard's Cake Stop. Feeling as though a great weight had been lifted from their shoulders, everyone exchanged strained glances - although only Lucy and Sarah met Simon Heap's eyes. No one spoke.

Free of the Darke Fog, Thunder snorted and pulled away from Jenna's grasp. As he headed noisily back to his master's side Jenna let go and, to her surprise, saw a rat clinging to Thunder's mane.

"Stanley?" she said, but the rat did not respond. Its eyes were shut tight and it was muttering something that sounded like, "Stupid, stupid stupid rat." It did not look happy, thought Jenna.

Marcellus looked about anxiously. The border of a Darke Domaine was not a place to relax - this was where outriders patrolled, extending its boundaries, pulling the Domaine ever outward. He placed a finger on his lips for silence and, reverting to what Septimus called old-speak - as he did when a little tense - he whispered to Jenna, "Whither now, Princess?"

Jenna pointed at the lone rushlight, which illuminated the entrance to the Ramblings she had been heading for - a tumbledown archway covered in ivy and a purple flowering plant that grew out of untended walls in the Castle. The purple flowers were long gone in the dead of winter but the woody twigs of the plant hung down and brushed their heads as they stepped through the old stones into the hush of the Ramblings backwater.

Muttering, "I knaht uoy, esaelp eriter," Septimus was busy returning his Darke Disguise to its tinderbox. It folded up as helpfully as his House Mouse and as thin as a piece of tissue paper. He pushed the lid on tight and placed the little box back in his deepest pocket, along with the precious key to Dungeon Number One.

"I'll put a SafeScreen on the arch," he said. "At least that will keep the Darkenesse out for a little while longer."

Marcellus disagreed. "No, Apprentice. We must leave no clue that we have come this way. We must leave it as we found it."

Freed from the Darke Domaine, the party split into its natural alliances, which meant that Septimus and Simon got as far away from each other as possible. Marcellus and Septimus led the way. Simon - grabbed by Lucy on one side and Sarah on the other - stayed back, hiding his awkwardness at being near Jenna and Septimus by fussing with Thunder. Jenna hovered between the two groups like a magnet, attracted by the presence of her mother and repelled by the presence of Simon. Eventually, after two wrong turnings, Jenna joined Marcellus and Septimus and once again led the way.

The Ramblings was a strange place that night. Normally on the Longest Night it had a festive atmosphere. Doors would be flung open to reveal welcoming rooms with candles ablaze and tables piled high with delicacies from the Traders' Market. People would sit chatting with friends while children, allowed to stay up late and run free, played in the corridors. It was always a noisy, riotous time, fueled by plates of sugared biscuits and bowls of sweets, which were traditionally left beside the numerous candles that roosted on any free perch in the passageways.

But as Jenna led the way through the empty corridors, the only sounds to be heard were low, worried conversations drifting through closed doors and the occasional wail of a disappointed child. It felt, she thought, as though everyone was waiting for the onslaught of a violent storm.

But despite the sense of trepidation pervading the place, the candles still shed their warm light on the newly swept passageways and the bowls of biscuits and sweets sat untouched in their niches, although not for long. Jenna, who had had nothing to eat since "Edifice" with Beetle, spied her favorite iced pink rabbit biscuits and grabbed a handful. Septimus was particularly pleased to find a whole bowl of Banana Bears, and even Marcellus permitted himself a small toffee.

And so they walked on through the deserted corridors, Thunder's hooves clip-clopping as they went. The sound of the hooves brought one or two worried faces to the tiny, candlelit windows that looked out onto the passageways, and once or twice a door was held open an inch or two and frightened eyes gazed out. But the door was soon slammed and the candles quickly snuffed out - no one seemed reassured at the sight of the ExtraOrdinary Apprentice in the company of a witch, an ancient Alchemist, and that disgraced Heap boy - what was his name?

With Thunder in mind, Jenna led them up what was known as a trolleyway - a sloping passage with no steps. Trolleyways were longer, although not always wider, than the normal passageways, which often had very steep flights of steps. They were, naturally, designed for trolleys - an everyday feature of Ramblings life and an essential piece of equipment for people who lived on the top floors. "Trolley" was a term that covered a multitude of wheeled carts, the number of wheels varying between two and six. Those on the lower floors considered them to be the bane of Ramblings life, especially late at night when rowdy groups of teens would take them to the top of the steepest trolleyway and hurtle down through the various levels. Two-wheelers were the most popular for this sport, as they were easier to steer and had the advantage of being able to use the handles as brakes - if you leaned back at the right moment. But that night there was no danger of being run down by a trolley rider yelling, "Way! Way!" as a warning. All trolley riders were behind closed doors, fearful, bored and having to be nice to their visiting aunts - while the visiting aunts were deeply regretting their decision to come to the Castle for the Longest Night festivities.

With Thunder's hooves slipping on the worn surface of the bricks, the group trooped up the final and by far the steepest incline and stepped thankfully out into a wide passageway known locally as Big Bertha. Big Bertha wound through the top of the Ramblings like a lazy river and many tributary passageways branched off from it. This was one of the most difficult areas of the Ramblings to understand - some of the corridors were dead ends but did not appear to be, while others looked like dead ends but were not. Most twisted and turned in such a way as to disorientate even the most experienced traveler.

But Jenna had gotten top marks in her Ramblings Certificate and now it showed. Holding the key to the Big Red Door in her hand as if it were a compass, she led the way straight across Big Bertha into a corridor that appeared to be a dead end but was not. The wall at the end was a screen that had the entrances to two passageways hidden behind it. Jenna skirted the wall - which sported a line of multicolored pots, each containing a tall, thin candle stuck into a mound of boiled sweets - and took the right-hand entrance. It was a tight corner and Thunder had some trouble getting around it. Jenna wondered if Thunder might be a little spooked by the narrow confines, but for a horse that once lived in an old Land Wurm's Burrow, the Ramblings passageways were positively airy and spacious.

The passage led into a Well Hall - a circular space open to the sky. In the middle was the well, which was protected by a low wall and a wooden cover, on which stood three buckets of varying sizes. Above the well was a complicated pulley system that allowed heavy buckets to be easily drawn up from the huge fresh water cistern built into the foundations of the Ramblings. Rushlights cast a warm glow across the smooth, damp stones, which were warm enough to melt the occasional snowflake that drifted down. Set into the curved walls were some well-worn stone benches; pots with candles and wrapped sweets had been left on the benches and gave the Well Room a festive look. But even this popular meeting place was, like everywhere else, deserted.

Jenna waited by the well while everyone caught up. She caught Sarah's eye and smiled, hoping that Sarah recognized the place where she used to draw water and spend many hours chatting to her neighbors. But to Jenna's distress, Sarah just gazed blankly back.

"Nearly there," said Jenna, trying to keep cheerful.

"Hey, Jens, remember when you dropped your bear down the well and I fished it out in a bucket?" said Simon.

Jenna ignored him. She didn't think Simon had any right to use the old name he used to call her by before he kidnapped her and planned to kill her - no right at all. She spun on her heel and strode off into a narrow whitewashed corridor, which was lined with an array of multicolored candles. After a minute or so the party emerged once again into Big Bertha, having cut off a huge loop. They went around one more bend and then Jenna turned down a wide alleyway, which proclaimed itself There and Back Again Row. A few moments later she was standing outside the door to the room where she had lived for the first ten years of her life.

It looked different. No longer a scuffed and dismal black, the door was now painted bright, shiny red, just as it had been in what people still called The Good Old Days. In her hand Jenna held the precious key that she remembered Silas locking the door with every night, and which had hung on a high hook on the chimney the rest of the time. No one but Silas or Sarah had been allowed to touch the key because - as Silas had informed everyone one night when its hook had fallen out of the wall and Maxie had hidden the key under his blanket -  it was a precious Heap heirloom. The Big Red Door, complete with lock and key (with Benjamin Heap inscribed on the bow) was the only thing that Silas's father had left him.

Jenna knew exactly what to do with the key. She handed it to Sarah.

"You open it, Mum," she said.

Sarah took the key and looked at it.

Jenna watched Sarah anxiously. She glanced up and saw that everyone else was watching too. Even Marcellus. It felt like an eternity while Sarah Heap stared at the big brass key lying on her palm. And then, very slowly, recognition dawned in Sarah's eyes and the corners of her mouth flickered into the beginnings of a smile.

Hesitantly Sarah placed the key in the lock. The door recognized Sarah, and when she began, very weakly, to turn the key, the lock did the rest for her and the door swung open.