Beyond the footsteps of the greatest explorers and up past the reach of the trustiest maps there lies a kingdom called Erkenwald.

Here, the sun still shines at midnight in the summer, glinting off the icebergs in the north and slipping between the snow-capped Never Cliffs in the west. But it does not rise at all in the long, cold winters. Then, the nights bleed on and on and the darkness is so thick you cannot see your hands in front of your face.

This far north, even the stars do not behave as you might expect. And that is probably just as well because without Ursa Minor breaking a few rules we would not have a story at all . . .

The Little Bear, some call this constellation, but if astronomers knew the truth – if they could see into the heart of things and out the other side – perhaps they would have used a different name. For these seven stars are in fact Sky Gods, mighty giants carved from stardust, and the brightest of them all, the North Star, was the one who first breathed life into Erkenwald.

Such was his power that he only needed to blow the legendary Frost Horn once and the empty stretches of ice many miles below began to change. Mountains, forests and glaciers appeared. Then animals arrived: polar bears to roam the tundra, whales to glide through the oceans and wolves to stalk between the trees. Finally, the music of the Frost Horn conjured people: men and women of different shapes, sizes and colours scattered throughout the land.

As the years passed, these men and women formed three tribes: the Fur Tribe built tipis from caribou hides in a forest to the south of the kingdom; the Feather Tribe settled inside caves in the Never Cliffs to the west; and the Tusk Tribe built igloos along the cliff tops on the northern coast. Each tribe had their own customs and beliefs, but they lived in harmony with one another, sharing food whenever they passed and offering shelter when the weather closed in.

Because magic often lingers long after it has been used, the power of the Frost Horn hovered over Erkenwald, and as time went by the people learnt how to use it. They spun hammocks from moonlight which granted wonderful dreams; they trapped sunbeams in lanterns which burned through the winter months; they stored wind inside gemstones which granted their boats safe passage through stormy seas. And the people knew all was well in their kingdom whenever they saw the northern lights. For these rippling colours were a sign that the Sky Gods were dancing – and that meant the world was as it should be.

But darkness can come to any kingdom, and so it came to Erkenwald.

The smallest Sky God grew jealous of the North Star’s power and, seeking to rule Erkenwald herself, she pulled away from the constellation one winter night and plunged towards Earth. The North Star acted swiftly and trapped her in a glacier before she could spread her evil across the land. But the Sky Gods stopped dancing then because they knew that it was only a matter of time before someone heard the whispers of the fallen star calling out behind the ice.

And, before long, someone did.

One night, Slither, the shaman for the Tusk Tribe, was drawn to the glacier and he listened as the voice within promised him dark powers if he killed his chief and made it look like a plot brewed by the Fur and Feather Tribes using Erkenwald’s trusted magic.

Although the words were only whispers, they plucked at Slither’s heart and, believing all they said, the shaman slew the Tusk Chief while he slept with an enchanted knife. In the weeks that followed, distrust between the tribes gave way to hatred and faith in Erkenwald’s magic died. And it was then that Slither climbed back into his skin-boat and paddled beneath the cliffs towards the glacier.

The voice was still there, only it was louder now – as if the hatred between the tribes had given it fresh force – and this time Slither could make out the body of a woman behind the ice. She was tall and slim, with skin as white as marble and lips a cold pale blue. Her eyelashes were crusted with frost, her silver hair twisted through a crown of snowflakes and in her hand she held a staff of glittering black ice. Slither raised a palm towards the Ice Queen and, because this was a palm that had done a terrible thing, it melted the frozen wall before him and the woman stepped out from the glacier and into the skin-boat.

She held up her staff and thunder rumbled across the sky as every man, woman and child in the Tusk Tribe, now locked under the Ice Queen’s hold, stepped out of their igloos. They watched in silence as she pointed her staff towards the glacier she had been trapped inside. An enormous chunk of ice broke free from its tip and slid into the sea, but it did not drift away. The Ice Queen waved her staff and a bridge snaked out between the cliff and the iceberg, tethering it in place. Then domes, turrets and towers formed, shooting out of the iceberg with ear-splitting cracks until, finally, there stood a shimmering fortress carved entirely from ice.

Winterfang Palace was born; the reign of the Ice Queen had began. And to reward his loyalty, the Ice Queen gave Slither command of the Tusk Tribe and taught him how to wield the very darkest magic.

Spring came, then slipped into summer and, from afar, the Fur and Feather Tribes watched as the Tusks left their igloos every morning and walked across the bridge into Winterfang Palace. A battle was brewing – the Fur and Feather Tribes could hear the sharpening of spears and hammering of shields – and, fearing that the Ice Queen meant to drag all the tribes under her command, they launched an attack on Winterfang.

But to fight for something you believe in requires trust as well as courage – and there was not enough trust between the Fur and Feather Tribes that day. There was no faith in Erkenwald’s magic either and the weapons of even the most skilled fighters were nothing against Slither’s Tusk warriors. They fought with black ice javelins and shadow-shields and soon every man and woman from the Fur and Feather Tribes was imprisoned in the palace towers. Slither’s warriors seized a child, too – the only one who had been granted a place in the battle – because this was a child marked out by the Sky Gods, a child that the Ice Queen had been looking for ever since she fell from the sky.

The other children remained beyond the Ice Queen’s grasp and, though Slither’s warriors scoured the kingdom all through the summer and on into the winter, they found no trace of them. Erkenwald became a land shrunk to whispers, but, because a fallen star can only survive one midnight sun on Earth before its magic fades, the Ice Queen set about finding a way to gain immortality.

Voices, she discovered, were the key, and if she could swallow the voice of every man, woman and child in Erkenwald before the next midnight sun rose she would possess the eternal life she craved. By midwinter, a new sound rang out from Winterfang: an anthem played on an organ made of icicles, accompanied by a choir of voices that once belonged to the Ice Queen’s prisoners.

The anthem called some children out of hiding, so desperate were they to be reunited with their parents whose voices they could hear above the music, but most knew better than that. They realised that the stolen voices were a trap and they vowed to lie low until they could form a plan to defeat the Ice Queen and rescue their parents.

But some people are not very good at lying low. They have wandering limbs and fierce hearts and more often than not they have heads full of wild ideas. Our story follows two such children – an unlikely pair, some would say, but you cannot pick and choose who adventures happen to. They pounce when you are least expecting them, then they hurtle forward with surprising speed. In fact, once an adventure digs its claws in, there is not an awful lot you can do about it.

Especially when magic is involved . . .