Molly thumbs her way to the net settings on her phone and finds a list of nearby Wifi access points. Sure enough, among the usual home routers, there's an open network, and her heart skips a beat.
It's called HEYMOLLY.
She leans against the laundrette and thinks. It can't be coming from inside a house or a shop. It's a message from Danny, who was outside, chalking the pavement. And if he'd got inside somewhere, why isn't he answering his phone? It's got to be out on the street, but there's no electricity out here; nowhere to plug in a router.
There's only one answer, really, Molly thinks. It's a wireless hotspot - maybe one of those little 3G gadgets that gives you a broadband connection in your pocket. Danny's stashed it somewhere; somewhere not too obvious, but somewhere she'd be able to find it.
She starts off walking down the street, past the parade of shops, keeping an eye on the signal strength. As soon as it drops off to nothing, she comes back to Danny's chalk and sets off in the opposite direction. When HEYMOLLY disappears from the list again, she comes back again, and this time walks off back towards her bike, at right angles to her first two trips. The signal drops off a little quicker this time, and Molly has three points of a triangle.
She tries to imagine a point equidistant from all three. A little way off to her right, there's a row of houses, all with their plastic recycle bins neatly standing outside ready for collection; and as she gets up close, she spots a smear of yellow chalk on the top of the first.
Molly looks both ways, opens the gate, and as quietly as possible prises the lid off. Inside, just nestling on top of a green rubbish sack, is a sealed ziploc bag containing an expensive smartphone.
She fishes the bag out, liberates the phone, and clicks the screen on. The first thing she sees is M: RU OK? Her text message. Unread.
Oh, Danny. Where are you? What's happened?
There's something else in the bag, too - a stick of flash memory, the kind people use to move documents around between computers. Both phone and stick go into her satchel.
Suddenly Molly's dead tired. It's six a.m.; it'll be getting light soon, and there's nothing else she can do here. She puts the lid back on the bin, goes back to her bike, and starts the journey back home.
Molly's creeping up the stairs to her bedroom when her Dad calls her name; yells it, really, from the basement. He's up then, she thinks. Or maybe he didn't go to bed either.
"I'm coming, Dad," she says, and makes her way down.
Cyril Root is ensconced in his favourite armchair at one end of the big, dim, cluttered space he uses for inventing. There's a workbench along one side, covered in tools, circuit boards, chemicals in poorly-labelled flasks, dismembered bits of long-dead computers, and bins full of nuts and bolts. An old kitchen table in the middle of the room is the world's least organised filing system: teetering stacks of blueprints, magazines, and the output of his ancient dot matrix printer, accordion folds and all. Every available inch of wall space is given over to shelving, which seems to have been filled with books entirely at random.
There's a board laid across the wings of the armchair, forming a makeshift table in her Dad's lap. He's doing clockwork, today - the board's lined in soft felt across which is scattered an array of brass cogs and springs. As he looks up, smiling, she can see one rheumy eye peering at her through the big illuminated magnifying glass he has rigged up to a band around his head. His white hair fluffs out from underneath.
It's a pity he doesn't just look like a mad scientist, Molly thinks.
"You're up early! Come and sit down," her Dad says. Molly slumps in the chair next door, shifting a stack of New Scientists. This is where she used to come and play Go with him, back when he had the patience for it.
"Hi Dad," she says. "Sleep well?"
"Not slept yet," he replies, and Molly's heart sinks a little.
"We got those pills, remember? If you can't sleep..."
"I can sleep if I want to, young lady. I don't need your permission or your pills. And speaking of insomniacs, you've not been to bed yourself, have you?" Dad reaches up and clicks off the light on his headpiece. "I heard you sneaking out an hour or two ago. Where have you been?"
Molly forces a shy smile onto her face. "I couldn't sleep either. I'm sorry, I shouldn't nag you. I went for a bike ride." And then, feeling guilty about it, she derails him. "Are you building something?"
Dad leans forward, and there's a light in his eye that owes nothing to batteries. "Yes! I think this is a real advance on those clockwork generators you get in torches and radios and things. Excellent stuff, but the efficiency is limited. Now this…" And he's off. Her night-time excursion is completely forgotten in a spray of gearwheels.
It's past seven when Molly finally manages to extricate herself; the mainspring of Cyril Root's enthusiasm is not even close to unwound, but she knows from experience when she's listened long enough to avoid upsetting him, and makes her excuses. He gives her a twinkly little wave as she climbs the stairs, and she knows he'll be up all day.
Back in her black-and-white room she shoos Stanley, the Roots' enormous marmalade cat, off her bed, and unpacks her satchel. Molly has always had a horror of untidiness, and soon everything is put away in its appointed place. Everything except Danny's phone, and the memory stick.
Molly sighs. No sleep for her for a bit.
The phone's almost empty: no contacts, no email, no pictures. In fact, she'd say it was fresh from the shop. It's a nifty and expensive gadget, running Android, and as far as she can tell it's on a pay as you go contract. It's an emergency phone, Molly thinks. Something you'd take with you if you were on the run, so you couldn't easily be traced. Thinking about it, she prises the back off and pulls out the SIM card. If someone does start to track it, she doesn't want it broadcasting her location.
She reboots the now SIM-less phone and checks out the apps, which are all equally empty of data - except the ebook reader. Molly taps her way into the library and finds ten books. Odd, she thinks, and has a look at one. But Pride and Prejudice does indeed seem to be Pride and Prejudice.
The memory stick is more interesting. Molly plugs it in to her laptop and dumps the contents into a sandbox - a part of the drive that in theory viruses and malware can't escape from. She's sure Danny wouldn't leave her an infected flash drive, but it's force of habit. She never lets anything into one of her machines that she doesn't trust 100%.
There are three folders on the drive. One, just from browsing the README files, seems to be full of hacker tools. There are dozens of programs for all kinds of nefarious purposes - password crackers, network snoopers, keyloggers, trojans and what looks to Molly like a particularly nasty suite of viruses safely locked up and dormant; it's the software equivalent of walking past the tiger cages at the zoo.
The second folder contains a single huge file that seems to be some kind of encrypted archive. In theory, it could contain a few million copies of Pride and Prejudice, or the whole Star Wars trilogy in high definition. (To Molly, there are only three Star Wars movies.) But there's no way of telling, because she doesn't have the password to get into it.
She moves on to the third folder. Inside is a much smaller file, which is unfortunately just as encrypted, and a text file that contains nothing but the word 'DIFF'.
It's too late for Molly to go trying to crack passwords now. In fact, it's too early in the morning - the sun's up and Stanley is perched on the windowsill taking in the rays. She shuts down the laptop, pulls the black curtain closed, ejects the indignant cat and goes back to bed.
She lies there for a minute, in the dark, her mind whirring. What am I into? She's scared for Danny, scared for herself. Scared for her dad. I should forget about this. Get out. Dump the flash drive and the phone. But she can't switch off the part of herself that only cares about solving puzzles; when she closes her eyes, she sees black and white stones, clicking into place. There's a pattern there that she can't quite see the edges of….
When she wakes up, it's to the news that Danny Solomon is dead.
The next instalment of Root will be available tomorrow
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