Jenna clung to the horse's wiry mane as Simon cantered across the Palace lawns, scattering all the lawn lizards that Billy Pot had only just rounded up.

Jenna loved horses; she had her own horse, which she kept in the stables and rode every day. She was a good horsewoman and a brave one, too. So why did she feel so scared? Was it, she wondered, as Thunder hurtled through the Palace Gate at breakneck speed, because Simon rode the horse so angrily, and roughly, too? Simon wore a pair of sharp spurs on his black boots and they were not just for show. Jenna had already seen him touch the horse's flanks with them twice, and she didn't like the way he pulled so sharply on the reins either.

Simon galloped down the middle of Wizard Way. He looked neither right nor left and paid no attention to anyone who might be crossing the roadas Professor Weasal Van Klampff happened to be doing just at that moment. The Professor, unaware of the fact that Marcia was on her way to see him, had something to tell Marcia, something that needed to be said well away from the remarkably acute hearing of his housekeeper, Una Brakket.

As Professor Van Klampff wandered absentmindedly across Wizard Way, rehearsing in his mind how he was going to explain his suspicions that Una Brakket was up to somethingalthough he was not sure whatthe last thing he expected was to be knocked down by a huge black horse thundering by. But, unfortunately for the Professor, that is exactly what did happen. And when he picked himself up, bruised and shaken but otherwise unharmed, Professor Van Klampff could not remember why he was there at all. Did he perhaps need some more parchment ... a new pen ... a pound of carrots ... two pounds of carrots? The tubby little man with the half-moon glasses and straggly gray beard stood for a while in the middle of Wizard Way, being fussed over by the concerned Beetle and other assistants from neighboring shops and offices, shaking his head and trying to remember why he was there. Some niggling feeling at the back of his brain told him it was important, but it was gone. Weasal Van Klampff shook his head and turned back for home, stopping to buy three pounds of carrots on the way.

Thunder, meanwhile, was cantering headlong down Wizard Way, past the shops, printers and private libraries, where the proud owners were pottering about, setting out the special-offer manuscripts and end-of-line parchments. At the sight of the black horse charging by they stopped and stared for a moment, wondering what the Princess was doing with the dark horseman. What was the hurry?

In no time at all, Thunder reached the Great Arch. Jenna expected Simon to slow down and turn the horse around to go back to the Palace, but instead he yanked hard on the reins, and the horse veered abruptly off to the left and hurtled down Cutpurse Cut. The narrow street was dark and chill after the bright sun of Wizard Way, and it smelled rank. An open drain ran down the middle of the cobbles, and a thick brown sludge was flowing slowly along it.

"Where are we going?" Jenna yelled, scarcely able to hear herself above the clattering of the horse's hooves, which echoed off the ramshackle houses on either side of the alleyway and filled her head with noise. Simon made no reply, so Jenna yelled again, louder this time.

"Where are we going?"

Still Simon said nothing. Suddenly the horse took a left turn, narrowly avoiding an oncoming meat pie and sausage cart, and skidded on the slime that ran beneath its hooves.

"Simon!" protested Jenna. "Where are we going?"

"Shut up!" Jenna thought she heard him say.

"What?"

"You heard. Shut up. You're going where I take you."

Jenna twisted around to look at Simon, shocked at the sudden sound of hatred in his voice. She hoped she had misunderstood what he said, but, when she saw the coldness in his eyes, Jenna knew she had heard right. A sharp chill of foreboding jumped through her.

Suddenly the horse changed direction again. It was almost as though Simon was trying to shake off anyone who might be following them. He yanked on the reins, pulling the horse violently to the right, and Thunder plunged into Squeeze Guts Slip, a dark passage that ran between two high walls. Simon's eyes were two slits of concentration as the horse tore down the narrow passageway, its hooves sending up sparks from the flints beneath them. At the end of the dark passage Jenna could see open daylight, and as they hurtled toward it, Jenna made a decision. She was going to jump.

As Thunder burst into the sunlight, Jenna took a deep breath, and suddenly, unbidden by Simon, the horse skidded to a halt. A small figure in green Apprentice robes had stepped out in front of them and was fixing the horse with a piercing stare. Thunder was being Transfixed.

"Septimus!" gasped Jenna, more pleased to see him than she had thought possible. "How did you get here?"

Septimus did not answer. He was too busy concentrating on Thunder. He had never Transfixed anything as big as a horse, and he wasn't sure if he could talk and Transfix at the same time.

"Get out of my way, brat!" Simon shouted. "Unless you want to get trampled." Angrily Simon spurred the horse on but Thunder refused to budge. Jenna knew this was her chance. Taking Simon unawares, she made a pe for the ground, but Simon's reaction was quick. He grabbed Jenna's hair and yanked her back into the saddle.

"Owlet go!" yelled Jenna, hitting at Simon.

"Oh, no, you don't!" Simon hissed in her ear, twisting her hair painfully.

Septimus did not react. He hardly dared move.

"Let ... Jenna ... go," he said slowly and carefully, his intense green eyes still fixed steadily on Thunder's eyes, which were wide open and showing a large expanse of white.

"What's it to you, brat?" snarled Simon. "It's none of your business. She's nothing to do with you."

Septimus stood his ground and kept staring at Thunder. "She's my sister," he said quietly. "Let her go."

Thunder shifted uneasily. The horse was caught between two masters and he didn't like it. His old master was still there in the saddle, almost part of Thunder himself, and, as ever, his master's wish was also Thunder's wish: his master wished to go forward, therefore Thunder wished to go forward too. But standing in front of him was a new master. And the new master would not allow Thunder to pass, however much his old master jabbed him in the side with his sharp spurs. The horse tried to roll his dark brown eyes away from Septimus's stare, but he could not move them. Thunder pulled his head back, whinnying haplessly, Transfixed by Septimus.

"Let Jenna go. Now," Septimus repeated.

"Or what?" asked Simon with a sneer. "Or you'll put one of your pathetic little spells on me, will you? Let me tell you this, brat, I have more power in my little finger here than you will ever have in your whole miserable life. And if you don't get out of my way now, I will use it. Got that?" Simon pointed the little finger of his left hand at Septimus and Jenna gaspedon his finger was a large ring with a Reverse symbol on it. It looked horribly familiar.

Jenna tugged her head away from Simon's grasp. "What's wrong with you, Simon?" she yelled. "You're my brother. Why are you being so horrible?"

In reply, Simon grabbed hold of Jenna's gold sash and twisted it hard in his left hand, while he tightened his grip on Thunder's reins with his right. "Let's just get this straight, Princess," he snarled. "I am not your brother. You are just some unwanted kid my gullible father brought home one night. That's all. You have caused nothing but trouble for us and you have ruined our family. Understand?"

Jenna went white. She felt as though someone had hit her in the stomach. She looked down at Septimus for help, and for a brief moment Septimus glanced up at her, as bewildered as she was. But in that very moment when Septimus met Jenna's gaze, Thunder knew he was free. The horse's nostrils flared with excitement, his muscles tensed and suddenly he was away, cantering at full speed into the sunlight and onto the cobbled road that led to the North Gate.

Stunned, Septimus watched the horse disappear. His head spun with the effort of Transfixing the horse, which had fought him all the while and had been nothing like the practice rabbit which Septimus was used to Transfixing. Septimus knew he had one last chance to get to Jenna, and he shook his head to try and clear the muzziness that the enchantment had left. Then, shakily, he Transported himself to the North Gate.