‘Someone’s left a terrible mess,’ Becks said, indicating some wood shavings that were spread across a walnut writing table. There was also an old cloth and a hammer and a chisel.

‘Yes, this was about where they were standing,’ Judith said. ‘By this desk.’

‘There’s no way the owner of this house left this mess here,’ Becks said, suddenly animated. ‘Because I’m telling you, there’s not a spot of dust anywhere, and these paintings are all perfectly spaced. I mean, look at them.’

Becks indicated the walls, and the other women could see that she was right. The fifty or so paintings were all placed at perfect right angles to each other.

Becks was almost wistful as she spoke.

‘Your neighbour was very tidy, I can tell you.’

‘You’re right about these tools,’ DS Malik said. ‘I checked over the house after Mr Dunwoody’s death, and there were no wood shavings on this table, and no chisel or hammer, either.’

‘Apart from that painting,’ Becks said, puzzled.

‘I’m sorry?’

Becks indicated a painting on the wall a few feet away.

‘That painting’s not quite straight.’

‘It isn’t?’

‘Not quite.’

DS Malik and Judith shared a look.

‘It is,’ Judith said.

‘It’s nearly straight, but it’s a bit off. Believe me.’

‘You’re at a crime scene,’ Judith said. ‘A scene where someone has been using a chisel, throwing a torch at me, and you notice that a painting is a bit skewiff?’

‘I prefer it when things are nice and straight,’ Becks said with a tight smile. ‘Do you mind if I …?’

Becks went over to straighten the picture.

‘You mustn’t straighten the picture,’ DS Malik said kindly. ‘This is a crime scene.’

Becks stopped, her hand hovering over the corner of the picture.

‘But … it’s not straight.’

‘I’m sorry, you can’t interfere with the scene.’

‘I mean, who’d even know?’

‘Me. And I’m the Acting Senior Investigating Officer here.’

‘But I’ll hardly touch it. Just a nudge.’

‘Becks!’ Judith barked. ‘Step away from the painting right now.’

‘I was only going to straighten it.’

‘But I think you’ve uncovered what the intruder was doing in here.’

Becks was stunned.

‘I have?’

But then, so was DS Malik.

‘She has?’

‘I think so,’ Judith said as she went over to look at the painting.

‘I don’t understand,’ Becks said.

‘You’ll see it when you see it,’ Judith said.

DS Malik went over and joined the other two women looking at the painting. It was mid-twentieth century, she guessed. Just three thick bands of colour. A deep red across the bottom third, a light grey in the middle, and a warm yellow covering the top third of the picture. The effect was calming, she thought.

‘I’m sorry,’ DS Malik said, ‘I don’t see it.’