Once upon a time, a hundred years ago, there was a dark and stormy girl.

The girl was Russian, and although her hair and eyes and fingernails were dark all of the time, she was stormy only when she thought it absolutely necessary. Which was fairly often.

Her name was Feodora.

She lived in a wooden house made of timber taken from the surrounding forest. The walls were layered with sheep's wool to keep out the Russian winter, and the inside was lit with hurricane lamps. Feo had painted the lamps every colour in her box of paints, so the house cast out light into the forest in reds and greens and yellows. Her mother had cut and sanded the door herself, and the wood was eight inches thick. Feo had painted it snow blue. The wolves had added claw marks over the years, which helped dissuade unwelcome visitors.

It all began — all of it — with someone knocking on the snow-blue door.

Although 'knocking' was not the right word for this particular noise, Feo thought. It sounded as though someone was trying to dig a hole in the wood with his knuckles.

But any knocking at all was unusual. Nobody knocked: it was just her and her mother and the wolves. Wolves do not knock. If they want to come in, they come in through the window, whether it is open or not.

Feo put down the skis she was oiling and listened. It was early, and she was still wearing her nightdress. She had no dressing gown, but she pulled on the jumper her mother had knitted, which came down to the scar on her knee, and ran to the front door.

Her mother was wrapped in a bearskin housecoat, just looking up from the fire she had been lighting in the sitting room.

'I'll do it!' Feo tugged at the door with both hands. It was stiff; ice had sealed the hinges.

Her mother grabbed at her — 'Wait! Feo!'

But Feo had already pulled the door open, and before she could jump back it slapped inwards, catching the side of her head.

'Ach!' Feo stumbled, and sat down on her own ankle. She said a word that made the stranger pushing his way past her raise his eyebrows and curl his lips.

The man had a face made of right angles: a jutting nose and wrinkles in angry places, deep enough to cast shadows in the dark.

'Where is Marina Petrovna?' He marched down the hall, leaving a trail of snow.

Feo got to her knees — and then lurched back, as two more men in grey coats and black boots stamped past her, missing her fingers by inches. 'Move, girl.' They carried between them, slung by its legs, the body of a young elk. It was dead, and dripping blood.

'Wait!' said Feo. Both wore the tall furry hats of the Tsar's Imperial Army, and exaggeratedly official expressions.

Feo ran after them. She readied her elbows and knees to fight.

The two soldiers dropped the elk on the rug. The sitting room was small, and the two young men were large and moustached. Their moustaches seemed to take up most of the room.

Up close, they looked barely more than sixteen; but the man with the door-beating fists was old, and his eyes were the oldest thing about him. Feo's stomach bunched up under her throat.

The man spoke over Feo's head to her mother. 'Marina Petrovna? I am General Rakov.'

'What do you want?' Marina's back was against the wall.