Judith got up her tablet computer and started checking through the history on her web browser, but that didn’t trigger any answers, either. But she knew she had to be methodical. So she went back to the very first web search she’d done after Stefan had died. It was the article on Stefan’s argument at Henley with Elliot Howard. She clicked the link and carefully read the article again, but the answer to the question she was asking wasn’t there. So she closed the web page down and reopened the next one in her history.

As Judith worked forward in time in her web history, a calm descended on her, the same calm she felt when she was compiling a crossword. She’d open a web page, read it carefully, and then close it down and open another.

It took an effort of will to stay focused, but she kept plodding, knowing she’d get there if she was patient.

And then she found it.

As fate would have it, it was the most recent web page she’d visited, and therefore the very last page she could check.

It was the article in the Marlow Free Press about Stefan Dunwoody’s riverside house. Judith couldn’t believe that she’d read it so recently and the salient fact from it hadn’t registered at the time. But since seeing the old photograph of herself, and remembering Becks’ comment, she now read it again with fresh understanding.

Mr Dunwoody laughs when I ask him why he bought a house on the River Thames. ‘I can’t swim and I’ve always hated everything to do with rowing, so you’d think it was strange me buying an old watermill. But I love the wildlife you get on the river. As long as you never make me get in a boat, I’m happy.’

It was so obvious! These few sentences revealed who’d killed Stefan Dunwoody.

And finally everything made sense to Judith. Why you’d want to kill Stefan Dunwoody, and then Iqbal Kassam and Liz Curtis. And why you’d use a Second World War Luger to do it. And why the killer then left a Masonic medallion behind at the scene of each murder.

Judith was so deep in thought that it took her a while to realise her phone was ringing.

She finally registered the sound and picked up the call.

‘Hello?’ she said into her phone.

‘What were you doing in my office today?’

Judith’s blood chilled. It was Elliot Howard.

‘I’m sorry?’

‘My wife told me you went into to my office when I wasn’t there. What were you doing?’

‘Where did you get my number from?’ Judith asked, trying to buy herself some time.

‘I know a lot about you, Judith Potts.’

‘You can’t call me on this number.’

‘And you can’t go into my office when I’m not there.’