Free The Skeleton Road by Val McDermid

immediately felt dumpy, unfit and uncool under her fierce scrutiny. ‘I’m DCI Pirie,’ she said, determined to seize what initiative she could. ‘Historic Cases Unit. I’d like to talk to someone about a piece of evidence we submitted to you yesterday.’
    The woman shifted a wad of chewing gum from one side of her mouth to the other. ‘I’m Tamsin Martineau and I’m the one you need to talk to,’ she said, an Australian accent evident even in those few words. ‘Come on through.’
    Karen followed her into a room dimly illuminated by computer screens. ‘I know it’s early days, but I was in the building.’
    ‘No worries,’ Tamsin said, settling into an ergonomic chair in front of a work station that featured three monitors and various black and silver boxes whose function was a mystery to Karen. ‘Drag up a chair.’
    Karen brought over the nearest simple chair and sat down. ‘Is there anything you can tell me?’
    The words were barely out of her mouth when she regretted them. Tamsin smiled like a woman who’s just been handed the keys to somebody else’s sports car. ‘Well,’ she said, drawing the word out tantalisingly. ‘Let me see.’ And she was off. ‘Your CSI said he thought it was a hotel key-card, and I’d put money on that myself. Theoretically, the card could still hold some data. But that data isn’t going to be much use to us. It’s not going to say, “No-Tell Motel room three hundred and two for the night of June twentieth in the name of Mr Bojangles”. No such luck. Truth is, it’s unlikely to contain much except a random string which matches the access key for the relevant hotel door at the time in question. If we got really lucky, it could also have markers that would indicate the nature of the booking.’
    ‘The nature of the booking? What, you mean how it was booked? Like, phone or Internet?’
    Tamsin gave Karen an impatient look, as if she were a small and stupid child. ‘No, I mean like, was it room only, or bed and breakfast, that sort of thing. Whether they’re allowed to charge to their room. Which would indicate that the hotel’s done a pre-authorisation on a credit card. Whether or not they have access to any additional facilities like a gym, a pool, an executive lounge. That in turn would help you narrow down which hotel the key-card is for.’
    ‘Right.’ Karen felt on safer ground here. ‘Like, if he had access to the gym and the pool, it’s not likely he was staying in a guest house in Leith.’
    ‘Got it in one. There might even be an expiry date and time, which’d give you a window on when he checked in. The only problem would be that the data held on these cards is almost always encrypted. They use a master encryption key which is unique to the property and set when the key system is installed. On the plus side, the encryption key is usually pretty short by modern standards. And because there aren’t too many manufacturers of these key-entry systems, there’s not so many algorithms to factor into the equation. So somebody like me can bust the encryption wide open in a couple of weeks or so.’
    ‘A couple of weeks?’ Karen couldn’t hide her disappointment.
    ‘Come on, Detective. You know that’s no time at all in my world. Hardcore decryption can take bloody months. But anyway, all of this is aca-fucking-demic. Because your key-card’s been sitting out in the open and most of the magnetic strip has flaked off like dandruff on a jacket collar.’
    Dismayed, Karen said, ‘Bugger.’
    ‘Well, yes and no. There’s a bit of data that I’ve been able to pull off it. And it turns out to be worth a lot more than whether or not Mr Bojangles had access to the executive lounge…’ Tamsin paused expectantly.
    Karen knew what was expected of her. ‘Really? That’s amazing. What did you manage to find out?’
    ‘Here’s the thing. If you jam a couple of cards together in your pocket, sometimes the data from one magnetic strip gets picked up by