To the ancients, Thule was a land beyond the edge of the maps, a northerly dreamland. It was a mystery for thousands of years, long thought to be an icy Eden, a place of exquisite beauty and unequaled purity. The lost world of Thule captured the imagination of poets, artists, explorers, and, most recently, writer Joanna Kavenna, who set out on a harrowing and exhilarating voyage of discovery. Her journey took her to Shetland, Iceland, Norway, Estonia, Greenland, and Svalbard—into the Arctic wilderness, over frozen seas and ice mountains—in search of this most haunting of northern places.

As she travels, Kavenna finds traces of earlier writers and seekers: Richard Francis Burton, William Morris, Anthony Trollope, and Norwegian explorer Fridtjof Nansen. But she comes to discover that a darkness also inhabits Thule. She finds ice-bound relics of the cold war. She unearths the story of the Thule Society, an offshoot of the Nazi party, devoted to the "purity" of the Nordic peoples. Part diary, part detective trail, The Ice Museum is a wonder voyage through landscape and myth, reminiscent of Lucy Jago’s The Northern Lights and Barry Lopez’s National Book Award-winning Arctic Dreams.

The plane is drifting downwards, falling towards the glazed countryside. The ice looks like silence, like the physical embodiment of nothingness. A paradox, a symbol expressing the inexpressible; here is the vivid realisation of absence. As the plane descends, the warning sounds insistently: LEAVE. A single syllable resounding across the smothered land. No point in coming here. The country is closed for the ice deluge, to be opened in the spring. The plane is plunging through a white sky, into banks of drifting cloud. The trees below are bleached, their branches bent under the weight of the snow. As the plane skids across the runway the trees blur into lines of whiteness.

Shaking their heads, the passengers disembark. A pale sun shines onto the rigid arms of the trees. I step slowly onto the frost-coated runway. A thick wind blasts at my body, forcing me to bend against it. A woman is signalling frantically, pointing at a bus. We all board, obediently.

In an icy landscape, it is hard to discern distance and gradient. Complex layers of vegetation are simplified into one dense line of thick snow-bound forest. Only the most violent features of the landscape remain - the most jagged and strange. Trees seem to be locked in the ice, bowed by the weight of their casing, like statues struggling to become free of a block of stone. The sun trembles above the horizon, casting squat shadows on the snow, waiting to sink into darkness again. When darkness comes, the ice shines under a bright moon.

The ice land is an anonymous world, the trees stripped of colour. The fjord is frozen, the trees are silver splinters; it is almost dark, though the day is hardly half way through.

I was travelling through northern lands, compelled by the endless indeterminacy of a myth: the land of Thule - the most northerly place in the ancient world. Before the regions north of Britain were mapped, there was a dream of a silent place, where the inhabitants lived under darkened skies through the winter, and enjoyed constant sunshine in the summer. Thule was seen once, described in opaque prose, and never identified with any certainty again. It became a mystery land, at the edge of the frozen ocean.

A Greek explorer, Pytheas, began the story: he claimed to have reached Thule in the 4th Century BC. He had sailed from the sun-drenched city of Marseilles to Britain. He sailed up to the north of Scotland, and then sailed onwards for about six days into the remote reaches of the ocean, until he sighted a land called Thule. There, so the story goes, the inhabitants showed him where the sun set on the shortest day and rose again soon after. In the winter, the land was plunged into darkness. Near Thule, the sea began to thicken, and Pytheas saw the sea, sky and land merging into a viscous mass, rising and falling with the motion of the waves. He turned away from the seething semi-solid ocean, and sailed back to Marseilles.

Mist, sea and land, a frozen ocean, a midnight sun in the summer, a twilight sky throughout the winter. Pytheas's account of his journey was lost, and no one could decide where Thule might have been. It left the story of Thule as a tantalising glimpse of a distant land. It was an empty page, its silent rocks inviting interpretation. With each new discovery in the north the name of Thule was evoked. The Romans reached the north of Britain, and claimed they had conquered Thule. Strabo scoffed at the idea of Thule, at the credentials of Pytheas; but Virgil imagined Augustus worshipped as a god, even in farthest Thule. Later, Procopius thought Thule was in Scandinavia, and wrote garbled anthropology about the Thulitae. The Venerable Bede called Iceland Thule; the medieval clerics described Thule as a place where the sun never shone, and the ice became as hard as crystal, so the inhabitants could make a fire above it. Petrarch mused on where it might be; Mercator fixed Thule at Iceland. Christopher Columbus claimed he had been there, long before he arrived in America. As the lands of the North were mapped, the name of Thule was moved around, from Iceland to Norway, from northern Britain to the tip of Greenland. Northerly latitude was enough, a midnight sun and a frozen ocean still more persuasive.

Nothing could be known for certain about Thule, and so the word was drawn into imaginative histories, rhetorical speeches, poems and novels and explorers' accounts. It was worshipped and parodied, cited in stanzas and drawn into rhetorical phrases. A long line of philosophers, poets, advocates and detractors referred fleetingly to Thule, from Boethius to Percy Bysshe Shelley. They cast it in a cameo, adding the word to a line of their prose or verse, using it to evoke pallour and the North. Alexander Pope wrote a slapstick interlude in The Dunciad, in which a fire was extinguished with a dank and clammy page of a poem about Thule. Charlotte Brontë put Thule into a gothic scene, as Jane Eyre sits, abandoned by her relatives, dreaming alone on a rain-drenched afternoon. She is reading a book about the Arctic; a reference to the lonely rocks of Thule propels her into a wild transport, as she conjures the bleak shores of Lapland, Siberia, Spitzbergen, Nova Zembla, Iceland, Greenland, with 'the vast sweep of the Arctic Zone, and those forlorn regions of dreary space, - that reservoir of frost and snow, where firm fields of ice, the accumulation of centuries of winters, glazed in Alpine heights above heights, surround the pole, and concentre the multiplied rigors of extreme cold.' Thule was the symbol for all of this, Brontë thought, all these dreams of beauty and fears of desolation. From Julius Caesar to Edgar Allen Poe, Thule suggested cold silent plains, the blank spaces of the remote northern lands, awaiting discovery and interpretation. '...To the west, to Hesperian darkness, and the shores of barbarian Thule,' wrote William Godwin, in Things as They Are. 'A wild weird clime,' Poe called it, a land on the way to Night, a strange unworldly place.

Thule was entwined with thousands of years of fantasies about what might lie beyond the edges of the maps. As the maps came to cover the world, Thule was bound up with the crusades of modern exploration. In the 19th and early 20th Centuries, as more and more travellers set off for the remote north, Thule recurred in explorers' accounts: Fridtjof Nansen from Norway, Richard Francis Burton from Britain, Vilhjalmur Stefansson from Canada, Knud Rasmussen from Denmark all sounded the cry Thule, as they travelled across the Arctic. Imaginative explorers filled in the blank moment of arrival with a devout incantation. Where the ice stretched away, and the birds plunged and dived, crying into the cold air, the explorers remembered Thule, pinning the word to the empty wilderness. "An evocative account of crossing frontiers—geographical, cultural, political and personal." —Timothy Garton Ash, Sunday Times (London)

"On a journey notable for its many dangers and lack of creature comforts, Kavenna's remarkable voyage takes her to those places once identified as Thule, including the Shetlands, Norway, Iceland, Greenland and, quite plausibly it turns out, Estonia. Exceptionally readable...reminiscent of Lawrence Millman's Last Places and Colin Thubron's In Siberia...compelling...beautiful..." —Paul Watson, Times (London)

"The Ice Museum is neither travelogue nor essay but the expression of a heartfelt passion for dark myth and the far reaches of our imagination. Hers is a wonder voyage which never seems to tire; it has a ceaseless enchanting energy that washes over the reader as if from those restless seas. She is poetic, bold, and brave in language ... it's an astoundingly self-assured debut. A sensitively poised, cherishable book." —Benedict Anderson, Independent on Sunday

"[Kavenna] has a natural gift for descriptive writing and for delineating the character of the curious people she encounters on her travels. The reader is left wondering where the author hopes to go next, what further will-o'-the-wisp will attract her; but most of all he is left hoping he will be able to go with her and enjoy another such stimulating read. Fascinating." —John Ure, Times Literary Supplement