Ragna Bjartursdottir pulled the sleeves of her jumper over her frozen hands and stared across Reykjavik’s old harbour. How many more girls’ bodies would she have to examine? How many more lives would she have to pick apart trying to find out who did this to them?

She slipped her hand into her pocket and brought out a silver hip flask engraved with a crested grebe and wrapped in a plastic evidence bag. It had been next to the body of the last girl and Ragna knew she’d seen the emblem somewhere before. She’d wrapped it carefully and squirreled it away before forensics had arrived.

It’d come back to bite her on the ass, she knew, but she needed time to think. He was usually so careful. This didn’t make sense.

This was the fourth girl. All of them killed the exact same way. Bloody, brutal and slow. The killer enjoyed himself, took his time and Ragna knew it was a him. A man who liked to see women suffer. A man so meticulous that no trace of him was ever found.

If only she could think clearly. The cold was biting into her, dulling her thoughts; she couldn’t remember the last time she’d slept for more than a few hours together. She thought back to the people she had spoken to. The fathers, the boyfriends, the weeping best friends. Did any of them stand out? Had anything they’d said seemed wrong? Why was the damned bird so familiar?

She needed to get inside. The darkness and the snow had begun to fall quickly, heavily, blanketing the harbour. She ducked into the nearest illuminated doorway. It was one of her regular drinking spots and Ragna sat at her usual seat at the bar. She nodded to Hjörtur, the barman, and he brought her two fingers of whisky with his customary silent bonhomie.

It was a dive. The floor was sticky with spilled beer and drunks nursed their spirits in filthy corners. Hjörtur pored miserably over a crossword, lank hair falling over his skinny face. But it was warm and there was whisky.

All the girls had been well off, from good families and young - no older than sixteen. Strangely the lab had reported that first three had all eaten the same meal, just before they died - white fish in a spicy sauce, potatoes and green vegetables. All had drunk champagne too - what sort of establishment would serve them alcohol? They were children for chrissakes and the rules in Reykjavik are strict, you could lose your license serving booze to under 20s.

Could they have been on a date? An older man with influence, perhaps? Ragna made a note to check the menus of every restaurant in Reykjavik to see who served this particular menu regularly.

When she stood up to go to the ladies Ragna didn’t see the Hjörtur’s eyes flick up from his puzzle and follow her with avaricious eyes. And when she returned to order a second double and ask for a packet of matches, he brought the whisky and lit her cigarette himself with a silver lighter, embossed with a crested grebe.