Logan McRae. Stuart MacBride

if they’ve geotagged their posts I could use that to cross-reference their location with the nearest cell-towers and did you know you only need four tagged posts to identify an anonymous account with ninety-five percent accuracy?’

      ‘Great! So, get online and—’

      ‘You’d have to access the customer dataset of every mobile-phone company in the UK to do it, but you could maybe get a warrant …’ Tufty stuck his bottom lip out, showing off his teeth in some sort of weird bulldog impersonation. ‘Ooh! Or I could try hacking in and—’

      ‘No! No hacking things!’

      He sagged, going from bulldog to dewy-eyed puppy. ‘But Saaa-arge!’

      Logan stood and hooked a finger at him. ‘Follow me, Caffeine Boy.’ Marching across the open-plan office with Tufty scampering alongside – laptop clasped to his chest again.

      ‘Not Caffeine Boy. Caffeine Boy’s a sidekick’s name, I’m … SUPERTUFTY!’

      Everyone turned to watch as he did the pose in the middle of the room.

      ‘Fighting crime, one bad guy at a time!’ Shadowboxing, one-handed. ‘Biff! Pow! Kerrrunk!’

      Yeah, there was no way Tufty was ever making sergeant. The top brass had a strict no-weirdos policy. Mind you, Karl had made it all the way to Inspector, so maybe it was more of a guideline?

      Logan knocked on Karl’s door, not waiting for an answer before opening it and ushering Supertufty inside.

      Karl was perched on his mushroom again, wearing a pair of big magnifying spectacles that made him look like a character in a sci-fi film. ‘Well, well, who’s this invading my sanctuary at this early hour? Hmmmmm?’

      ‘Oooh …’ Tufty stared at the collected computer kit in its racks and boxes. ‘Cool!’

      Logan thumped a hand down on his shoulder. ‘Tufty, this is Inspector Montgomery. Karl, this is Constable Quirrel. He’s weird, but harmless, so you’ve got a lot in common.’

      A wave from Tufty. ‘Hello, Boss. Or do you like “Guv” better? We can stick with “Inspector”, if that works? Ooh, Ooh, or how about, “Maz Kanata”?’

      Karl peered at him over the top of his big glasses. ‘I have no idea who that is.’

      ‘It’s this really, really wise old character from Star Wars: The Force—’

      Logan hit him.

      ‘Ow!’

      Idiot.

      ‘Tufty’s been looking into the Professor Wilson social-media thing, and he’s found something, haven’t you, Tufty?’

      ‘I have, Tufty.’

      ‘Intriguing.’ Karl patted the worktop beside him. ‘Pull up a stool, kind Sir Tufty, and let us break bread. Well, we can share a Tunnock’s teacake, but symbolically it’s the same thing.’

      ‘Aye, aye, Inspector!’

      Logan shook his head. ‘Don’t let him have any more caffeine. And if you need to put him down for a nap, do it somewhere no one’s going to fall over him.’

      Tufty hopped up onto a spare stool and beamed at Karl. ‘Have you heard about using geotagged posts to identify anonymous accounts from mobile-phone-cell-tower records?’

      Light the geek touchpaper and stand well back.

      Logan reversed from the room. ‘I’ll leave you to it.’ Closed the door. ‘God, imagine what would happen if they bred …’

      A shudder.

      Some things were too horrible to contemplate.

      Ah well, back to work.

      He’d nearly made it as far as his desk, when the main doors opened and someone backed in, arms full: Rennie, getting a bit on the chunky side, with a deep tan and bleached blond hair waxed into spiky curls.

      Rennie turned, slow and careful. A big box of doughnuts acted as a tray, heaped up with tinfoil parcels and greasy paper bags and two of those cardboard things designed for carrying six take-out coffees at one time.

      Logan nodded at the vast collection. ‘On a diet again?’

      ‘And I got you a Poseidon’s Surprise too, you ungrateful spudge.’

      What the hell was a Poseidon’s Surprise?

      Rennie winked at him. ‘How did you enjoy getting up at a proper time this morning? Bit of a strain after twelve months off?’

      ‘Like riding a bike. Barely even noticed the difference.’

      Liar.

      ‘Aye, right.’ Rennie raised his burden an inch, then lowered it again. ‘Little help?’

      Logan unloaded the tinfoil packages, bags, and hot drinks onto the nearest vacant desk. ‘Do me a favour and call DI King. Tell him I’ve commandeered Tufty for the morning. I don’t know if the silly wee sod’s even checked in for work yet.’

      ‘Tsk …’ Rennie sighed. ‘That’s what you get for recruiting an inferior sidekick. Look what happened last time you were lumbered with that eejit!’ He thumbed himself in the chest. ‘Sergeant Simon Rennie: shaves as close as a blade or your money back.’

      ‘Maybe, but Bevan won’t let you out to play till you’ve finished all your homework.’

      ‘Then, the dream team shall ride again!’ He put the box of doughnuts down, picked up a tinfoil package and tossed it to Logan. ‘Exit left, pursued by a bear.’ Rennie grabbed a tinfoil parcel of his own and headed for his desk.

      ‘Rennie! Where’s the—’

      ‘On Shona’s desk.’ He threw himself into his seat, unwrapped his breakfast with one hand and grabbed his desk phone with the other, ripping out a bite and dialling as he chewed. ‘Yellow? Yeah, I need to speak to Detective Inspector King.’

      Logan paid Shona’s Happy Birthday Grotto a visit. Nodded at the streamers, banners, and balloons. A DIY poster with ‘YOU’RE 46 TODAY!!!’ on it in cheerful chunky letters. ‘Nice to see they kept it classy and low-key.’

      All he got in response was a grunt. She didn’t even look up from her copy of that morning’s Scottish Daily Post. An army of squeezy bottles stood to attention beside her monitor: tomato sauce, brown sauce, fluorescent-yellow American mustard, sweet chilli, mayonnaise, barbecue – both smoky and sweet – and a thing of salad cream for the more sophisticated palate.

      Rennie’s voice floated across the room. ‘Hello, DI King? … Hi, it’s Sergeant Rennie from Professional Standards … No, no. Nothing’s wrong.’

      Another grunt from Shona.

      Logan rolled his eyes. ‘Why yes, it is lovely to be back at work, thank you for asking.’

      She sighed, then glanced up from her article. ‘You’re feeling better then?’

      ‘Not at this time of the sodding morning, I’m not.’ He unwrapped his parcel. ‘Ooh, fish finger butty!’ That called for a celebration, so he slathered it in a mixture of salad cream and tomato sauce, then took a bite. Crunchy and fishy and sweet and savoury all at the same time. Munching around the words, ‘Well? How bad is it?’

      ‘Being forty-six? Awful. I used to be a svelte young thing, Logan, pursued by the sexiest of gentlemen, I went on fabulous holidays and ate in the finest restaurants. And now look at me: it’s a red-letter day if I can get that sodding LaserJet to print double-sided.’

      ‘No, not being forty-six: DI King. In the paper. How bad is it?’

      She frowned at him. ‘Nope, still not getting you.’

      ‘Front-page splash.