As Mihn left, Isak saw men of the Brotherhood run down the walkway towards the advancing troops. Each one carried bottles with burning rags in the neck. They threw them down the walkway and as the bottles smashed, the stone caught aflame, creating a barrier to protect the fleeing soldiers. That done, the King's Men ran, collecting up the few stragglers yet to leave, cutting down the last few enemies, until they were on their way to safety.

Isak watched them join the crowd clustered around the keep's gate. The wall shook again; it was about to crumble. The pop and grind of splitting stone screamed in the air. He ran to the head of the stair; they were running out of time. The wall would give in the next few blows and Emin's troops would be caught in the open and slaughtered as they gathered at the small gate of the keep, waiting for space to move to safety. Behind him the wall groaned and lurched. Two huge blocks of stone fell inwards and crashed down. Isak grabbed at the battlements as the walkway shuddered underneath him. He looked around: the flames were still too ferocious to cross. There might still be time.

Carel was halfway across the palace gardens when he heard stones falling and he turned back to see Isak balanced precariously, ten yards from the breach – and then only five as another piece collapsed. Through the gap he could see pike-heads, black against the firelight behind. Any more and the mercenaries would walk straight in. He looked around and saw how many were fighting to get into the keep – and here came Count Vesna's companies sprinting towards them from the rear of the palace, desperate to reach the gate in time.

Carel turned back to look at Isak, then drew Arugin again as four men ran towards them from the nearest tower, outstripped by the solders who'd been there. They stopped dead as he stepped forward. Unarmed and dressed in bright colour, they had to be the king's mages.

'You four, do something to help him.'

One looked over at the silver figure on the walls. Isak was kneeling down on the wall with his shield raised above his head. The stair was within reach, but he wasn't looking at it.

'Help him?' another replied incredulously. He was young, little older than Isak himself. His orange and blue robes were expensive; they'd have looked impressive this morning, no doubt. Now they were stained and scorched. 'We've got to get away,' he explained.

'What?' Carel asked. 'Why?'

'He's calling down the storm, using his magic to bring it to him. The lightning will follow anything drawing magic. Please, let us pass!' He sounded desperate, as if he were pleading with every remaining ounce of his strength.

Before Carel could reply, Commander Brandt appeared. 'What's he doing up there?' he asked. The watchman seemed furious more than anything else. His battered armour was covered in blood, but if it was his own the man didn't seem to have noticed.

'Buying us some time. If they breach it now we'll be slaughtered.'

Brandt looked back at the men fighting to get into the keep, then at Isak.

'He's not going to manage it alone. Look.' Brandt pointed to the intact side of the wall where the mercenaries were slowly making their way forward, throwing corpses on to the roaring flames to smother them.

'You.' Brandt grabbed the oldest of the mages. 'The enemy were throwing men up on to the walls by magic – can you do that?'

The man looked blank for a moment, lost in panic, then his face cleared. 'I think so, Commander, it's a simple spell. With four of us together, yes.'

'Good.' Brandt drew his sword, causing the mage to shrink back in fear. 'Then get me up there now, or we're all dead.'

'We'll need time-'

'You don't have it. I know about magic: draw as much as you can and get it done. If I'm still here in half a minute I swear you'll be the first to die.'

The mage opened his mouth to object, then looked again at the bloody sword and slammed it shut. He walked around Brandt until he could see Isak over the commander's shoulder. Taking hold of an object at his belt he took a deep breath while the other mages stepped

forward to place their hands on his shoulders and lend their strength. He closed his eyes, almost giddy with the rampant magic in the air. The mage's eyelids shuddered with panic as he felt the power flowing in from the other mages. It felt like an age as he lifted his trembling hand; the energy inside was scorching his fingers as it waited to be released – and then, suddenly, the magic took over and his palm slammed against Brandt's cuirass. He felt the raw power blossom all around and the commander falling away before unconsciousness enveloped him.

'By the eyes of Fate, who's that?' The Kingsguard pointed over the battlements as they watched a figure land heavily a few yards from Lord Isak.

'Gods, that's Brandt,' muttered the king as the figure clambered to his feet. A line of mercenaries were inching towards him. 'Don't just gape, you fools, help him!'

Those soldiers with bows began to fire down on the figures edging cautiously towards the commander. Flames dripped from the walkway as Brandt started slashing wildly at the lead soldier, who was nearly upon him. The man slipped on the bloody stone and landed on a burning patch, setting his own clothes alight.

As Brandt jumped back, the man pulled himself up and fled back towards his own troops, who shrank away from the burning soldier. The commander found his footing on the now-sloping walkway and backed away from the flames to where Isak knelt, motionless. The burning man was flailing madly at his comrades, then he tripped on the corpses at his feet and set them alight too.

'What's happening?' demanded Carel as he appeared in the narrow doorway and barged out to where King Emin stood. Sheer exhaustion made him put pride to one side and reach for Doranei's shoulder to steady himself; instinct was all that was keeping the veteran Ghost going now, for his arm was bleeding badly and he was ready to retch from fatigue. But Carel was a professional, and his boy was still out there. Somehow he found the strength to continue.

'Lord Isak seems to be casting some sort of spell.' The king pointed upwards. 'Look at the sky – that's not natural.' They all looked at the angry clouds roiling in the air above Isak. Even the gigantic silver-clad white-eye seemed insignificant against that brooding mass of violence.

'The mage said he was calling down the storm.'

'Well, it looks like it's about to hit.'

The wall shook again, a deep rumble that rose to a tortuous cracking as a ten-yard stretch ripped away and collapsed inwards. Isak hadn't moved, but everyone could feel the pressure in the air mounting. They knew something had to give soon. Near to him, Brandt attacked the advancing troops with reckless abandon, putting everything he had into a furious volley of blows.

'He's trying to take on an entire army,' cried one young Kingsguard soldier, 'but he's just a watchman.'

'Just a watchman, boy?' roared the king, anger flaring from nothing to a holy terror. 'He might be saving your life!'

Brandt took another blow on the shield and lunged up at his attacker's throat. The man fell, but another stepped forward and caught Brandt on the shoulder. He reeled, crying out in pain, but the sound was lost as a bolt of lightning crashed down on to the tower where the mages had stood. For a moment the men on the wall were frozen in time, as were the figures scrambling through the breach and spilling out into the scarred gardens. Then the tower was struck again, then the wall, then the ground, again and again. The storm was upon them, called by the Lord of Storms himself.

'As the shadows rose and the enemy appeared on all sides, Nartis spoke to the heavens. The storm obeyed his call and unleashed its legions – and he rained terrible fire down upon that place of death,' intoned Carel. There were tears in his eyes as he spoke. A few Kingsguard men turned with questioning faces as the air was split with fire and the voice of the storm raged unchecked, lashing down one bolt after another.