Everything had seemed nice and clear for a short while, all pointing in the direction of Isobel Sturridge being guilty – or at least Sellers had thought so, though her possible motive had remained elusive. Everyone else had appeared to think so too, until Sellers had gone to Josh Norbury’s flat and found Oliver Halliday’s book – since when Simon had been insisting he knew everything, while refusing to say a word about what this ‘everything’ might be.

Sellers had fielded a phone call from a furious Neil Dunning earlier in the day. ‘What’s wrong with your chain of command up there?’ Dunning had raged. ‘Kombothekra needs to get Waterhouse in line, or, if he’s not up to it, let Proust do it. Is this Isobel Sturridge person Billy or not? If not, who is? You lot are a fucking anachronism! You’re a joke. Nowhere but the Culver Valley would a detective – a DC, for Christ’s sake, not even a DI – get away with swanning around claiming to know all the answers and refusing to pool his knowledge.’

Sellers, thinking of Lane Baillie and what she might advise, had told Dunning he understood his frustration and sympathised; being Neil Dunning, in the present circumstances, couldn’t be easy. That had mollified him a bit.

‘My true enemy – or one of them – is anyone who can write about a serial killer three times a week and not once mention Josh Norbury, who’s just as dead as the four female victims,’ Simon was saying to Sondra Halliday.

She scowled. ‘It’s not my job to care about Joshua Norbury. I’m a feminist. Violence against women and girls is my concern. It’s my work. That’s why I don’t centre everything around Norbury, or feel obliged to refer to him every time I write or speak about Billy having murdered four women. Tell me this: while he was alive, did Norbury care about the liberation of women? Did he ever challenge the status quo, or own his part in the subjugation of the subordinate sex class? Prove to me that he did and I might care about him.’

‘We need you to do something for us,’ Simon told her. ‘It’s important.’

‘Wash and iron your undies? Make you scrambled eggs on toast?’

Simon pulled a folded sheet of paper out of his jacket pocket and put it on the table, print-side down. ‘I need you to send this to Lifeworld, word for word, not changing so much as a comma, and tell them it’s your next column. Let them publish it. It has to be published in two days’ time, not before – not even online. No sooner than forty-eight hours from now.’

Sellers wondered why this time lag was necessary. There was a lot Simon was keeping to himself, apparently: not only the identity of Billy Dead Mates.