As a journalist, her mother was unfailingly accurate in matters of grammar and punctuation, but in this case it looked as if she’d written the card in a rush. I definitely Hope you did too. The words definitely Hope was not only bad English, hope had a capital H, an obvious error and one Silva was positive her mother wouldn’t have made.

Holm was ensconced in his little office under the stairs by eight the next day. His head was clear and his body had recovered from the hammering he’d given it on the night out with Palmer.

After Javed had dropped the bombshell about the tweet, Holm had sent the lad away. He needed time to think, and Javed talked ten to the dozen. There was barely a gap between his words for a breath and he’d wanted Holm to act on the information immediately. They should go to Huxtable, make a request to Twitter for more information on the account that had sent the tweet, raise the terrorist threat level, possibly recommend cancelling the weekend’s football fixtures. The latter suggestion had caused an ache to thump in Holm’s forehead which had nothing to do with the copious amounts of alcohol he’d consumed.

‘Enough,’ he said. ‘Go home and act normally. We’ll talk tomorrow.’

Javed had slunk away like a scolded dog and Holm once again felt guilty for raising his voice. Still, it couldn’t be helped. He needed space to himself.

Back in his flat he’d made himself a strong black coffee and sat at the kitchen table, a pencil and a pad of paper at the ready. Now, in the office, he pulled out the pad from his briefcase and looked at his scribblings. Holm didn’t really understand Twitter or social media or why so many people lauded a medium that seemed to exist merely to allow the sharing of either pictures of cute animals or vile abuse. He did, however, understand the world of espionage, the world of covert communications. Except the tweet hadn’t been covert. It was hidden in plain sight. An account directly referencing Taher and Holm. There were a couple of possibilities he considered and discounted. First, it was a stunt by Palmer or another of his colleagues. No, the security services didn’t do pranks like that. It would be too easy for such a joke to backfire and endanger personnel in the field. The second possibility was the username was simply a coincidence. That seemed unlikely because the contents of the tweet mentioned the innocent one – which was what the name Taher meant, and the chance of random characters resolving to a cipher of RAVEN and the numbers of Holm’s birthday was astronomical.

Which left the real possibility that somebody was trying to communicate with him and Javed. Somebody, Holm reckoned, who was prepared to betray Taher.

Who will listen to my voice? Who will stop this madness?