The stench was coming from the kitchen. There was often a greasy haze in Vendela’s apartment when her neighbours down below were frying food, but this was something different.

‘Try leaving the window open in the afternoons,’ the chair of the committee had suggested when she called to complain.

A ridiculous idea – how was that going to improve the situation? However, in spite of her scepticism, Vendela gave it a go. She left the window open for several hours, and when she closed it the odour was just as bad as before.

She went downstairs and rang the bell of the apartment on the far left; the occupants were a very nice family with small children. They even invited her to dinner occasionally. Elvira looked stressed when she opened the door. She was holding the latest addition, a two-month-old baby who was screaming so loudly that Vendela was quite taken aback.

‘I’m a bit busy at the moment,’ Elvira said. ‘Is it urgent, or can I pop up and see you when things have calmed down?’

She smiled, as she always did, but the smile didn’t reach her eyes. Vendela wished she hadn’t come.

‘I was just wondering if you’d noticed a strange smell over the past few days,’ she said.

Stupid question – the whole stairwell stank. Elvira shushed the baby.

‘Yes – Paul thinks there might be a dead rat somewhere.’

The same thought had occurred to Vendela. After all, Stockholm was practically heaving with the creatures. They must get into buildings and die there all the time. She shuddered and drew her cardigan around her body. It always upset her when something in the block went wrong. As a self-employed person with a home office, she was dependent on things functioning properly. Otherwise she couldn’t get on and started missing deadlines, which didn’t impress those who supplied her with work.

‘I’ll take a walk around, see if I can suss out where it’s coming from,’ she said.

She decided to start in the basement, see if she could locate the source of the problem. If it was a dead rat it ought to be down there where the laundry room and storage facilities were, or maybe on the ground floor. It seemed unlikely that it would have got into one of the apartments.