Back in the Foxhound, speeding along the dirt road towards the base, Silva had ribbed him. ‘I thought you were a spy. James Bond, Jason Bourne, derring-do and all.’
‘Fuck that.’ Sean had given her a grin and tapped his head. ‘I’m an intelligence officer and my brain tells me to steer clear of bullets.’
‘Right.’
‘Forgive me for saying so, but force alone never wins the battle.’ Sean nodded at Silva’s rifle. ‘Analysis of the situation leading to the formation of a specific strategy for victory will.’
‘And what’s your strategy for victory?’
Sean smiled, his intent now obvious from his flirtatious look. ‘To ask you to have a drink with me tonight when we get back to the base.’
It had started there and ended, at Silva’s behest, three years later. Their relationship had been conducted on Skype and WhatsApp and in the short periods of leave they could arrange to coincide. Silva had been in Afghanistan, then back to the UK, and then to Afghanistan again on what would be her final tour before she was court-martialled. Sean had flitted between Baghdad, Kabul, London and the US. He’d visited her once when she’d been in the glasshouse and she’d told him not to come again. When she’d been released she’d met him in London during one of his stopovers and that was the last time she’d seen him.
‘Where are you, Sean?’ Silva asked. From the delay and crackle on the line she suspected he was using a satellite phone and calling from somewhere remote. She felt her defences rise as if she needed to protect herself from something. Almost unconsciously she hardened the tone of her voice. ‘And what do you want?’
‘I’m in Plymouth, Becca. And I want to see you.’
The first week of Holm’s pretend investigation panned out pretty much as he expected. Colleagues poked their heads round the door of the little office to see what he was up to, Huxtable nodded with approval when she saw the fake brief Holm had written on animal rights groups, and Javed continued to slurp his coffee, crunch his biscuits and clip his nails in a way that annoyed Holm immensely.
The two of them monitored the Twitter account of the mysterious user known as TCXGP1505, while Holm set up the dummy animal rights operation. He phoned his contacts and let them know what he was up to and made requests for information from various agencies. A policy book was created and a budget drawn up. Javed scoured the internet for extreme material and organised everything in a database.
The initial excitement Holm had felt when Javed had shown him the tweet slowly ebbed away though. TCXGP1505 remained silent. The account followed nobody and had no followers. The sole tweet was the one in Arabic that referenced the innocent one.
‘I don’t get it,’ Holm said. ‘I’m beginning to wonder if our source, if that’s what it was, has been compromised.’
Javed looked up from his screen, horrified. ‘You mean taken out?’
‘It figures. What else can explain the lack of a follow-up?’
Javed shrugged. ‘If it’s somebody close to Taher then the risk must be enormous. Perhaps they got cold feet.’
‘Perhaps.’ But Holm didn’t think so. They’d sent one message. The tease. The wake-up call. The bait. If the source was still alive there had to be another one along at some point.
And so it proved.
On Friday afternoon, as Holm was deciding whether to take up Palmer’s offer of a couple of jars after work, Javed lurched back in his chair.
‘We’re on!’ The chair rocked violently as Javed changed direction and hunched forward, his face inches from the screen. ‘What the…?’
Holm stood and moved over. The tweet was a sequence of numbers, seventeen in all.
‘18, 18, 14, 0, 21, 11…’ Javed began to read them. He turned from the screen. ‘Another code.’
‘Makes sense, after all, it’s what we spooks do, isn’t it? Codes and dead-letter drops and listening to phone conversations. Least that’s what I believed before I signed on. More fool me.’
Holm read the numbers back to himself and tried several simple substitution ciphers in his head. The first three tries were gobbledygook so he went across to his desk and grabbed a few sheets of paper and a couple of pencils. He handed a sheet and a pencil to Javed. ‘Let’s see what that brain of yours can do.’
Holm wrote the numbers out large. Then small. Then in a scrawl. Then neatly. He tried placing them in a clock face, moving round the dial in a random fashion. He multiplied the numbers together. Divided them. Added them.
‘You got something, boss?’ Javed said. He appeared to have a similar idea to Holm as he was using the calculator on his phone to perform some kind of complicated transformation. ‘Because it’s beyond me.’
‘Nothing, and we can’t very well give it to the bods at GCHQ. We have to work this out ourselves.’
‘They want us to get this,’ Javed said. ‘Else why bother?’
Holm read through the numbers once more. There were, of course, certain codes that couldn’t be deciphered. They were uncrackable and offered perfect secrecy even against the most powerful supercomputer.
‘I’ve got it,’ Holm said, realising what the cipher was. ‘These numbers are from a one-time pad.’
Javed nodded, understanding immediately. ‘So we’re stuffed?’
‘Unless we can find the key, yes.’
A code created with a one-time pad used a sequence of letters or numbers to encrypt the message. Without the source material, decryption was impossible.
Holm screwed up his piece of paper and lobbed it towards the filing cabinet where it bounced off the front and fell into the waste paper bin. He shook his head.
They want us to get
