It was late when Nick finally left the café. Through his exhaustion he noted that the streetlights were already turned down to their lowest setting, barely illuminating the empty streets. Stepping into the street, the lights around him brightened slightly and as he turned to the right, the lights up ahead also brightened, drawing him towards home.

The day had been a long one, and filled with an overabundance of trepidation and excitement. It felt like a week since he had crept into his observation bubble that morning, and he was very pleased that he had declined Rashi's offer of a beer. Recalling the remains of the cold burger left on the plate and contemplating his still empty stomach, he did not want to think about what alcohol would have done to his tired state of mind. As it was, he felt something far too similar to a hangover creeping up on him.

The excitement that had carried him through the day was ebbing, and as he finally stumbled through the door to the apartment he was torn between heading straight to bed or to explore the mystery signal further. Locking the door behind him and hanging his jacket, he idly noticed Sae's coat on the other peg. He wished he could talk to his sister about the current weirdness, and was wondering if she was still awake. Listening to the quiet of the apartment Nick went into the large kitchen which also served as their main living room; simple but quality appliances in one corner, a seating area with a couch and a comfortable chair in another.

Sae wasn't there, and probably in bed.

Standing by the fridge, drinking a glass of cold water and letting his brain zone out for a few minutes, Nick gently prodded his fatigue. Tired; a part of his brain was still fired up and eager to explore the mystery signal further. If he went to bed now, Nick didn't think he would be able to actually sleep any time soon.

Finally deciding to work himself into sleep inducing exhaustion, Nick moved over to the seating area and sat down in the leather chair. Closing his eyes, he called up his mindpal's main desktop interface and opened up the applications he needed. His fingers gently tapping against the chair armrests, he brought up the latest analysis results.

--

A total of around 1300 terra-weirdo-bytes had been downloaded and if this went on all night he would get dangerously close to his total drive allocation. More importantly; if he had not already triggered some detection thresholds he was bound to raise some eyebrows very soon. Through his tiredness, Nick realized that he had to do something about that right away, and he thought he had just the solution.

Standing up from the chair, he went into his room and looked around. He knew he had a storage qube somewhere, and after rummaging around for a few minutes Nick found it in a bag behind his desk. A product sample he had picked up at work some weeks back, the qube promised a storage capacity of 25 kTB. When he won it at their monthly raffle, he thought it was pretty pointless. Who needs storage that you need to carry with you and physically connect to, when the mindpal drive was always available?

Walking back into the kitchen, he was happy that he had kept it.

Sitting back in the chair, connecting the qube through a cable to the data port at his hip, he initialized the drive with his identity and encryption keys. As he completed the handshake with his mindpal the drive appeared as a new icon in front of his eyes. After that it was a simple task to mirror the weird signal file into the storage qube, and setting up the mindpal drive as a simple transfer buffer. From now on, the laser array signal would be stored automatically on the qube.

Having completed what he now recognized was a very useful piece of digital housekeeping, he dove back into the data.

The scripts he had started earlier in the day were producing a range of interesting results; the protocol decoders had managed to build some strong assumptions about what the different protocol headers did. A checksum was apparent, as was the routing part of the packet. A couple of distinct fields did not make much sense, but seemed to be some type of flags. The most interesting part of course, was the data field and Nick felt sparks of excitement when he realized that the decoder had managed to built what looked like a simple data dictionary: The individual bits had been arranged into 4096 distinct units and a frequency analysis revealed the most common letters. Staring at the data and wondering what he could to next, Nick felt his thoughts carried away on a stream of nonsense signalling the arrival of sleep before his brain finally shut down with exhaustion.

His last conscious thought registered the alert popping up in his fading vision: Transfer Completed.

--

The transition taking him from dream back to wakefulness was performed by two instruments: The urgent and insistent beeping of his alarm clock played the familiar rhythm track, while the vocals were carried by a clear note of the smell of coffee... Coffee?! His eyes shot up, and he started at the face looking directly into his. Dark brown eyes, conveniently short hair and a slightly forbearing and sympathetic smile topped a small, slim and darkly clad body.

His sister was reaching out her hand, waving a mug of coffee under his nose and introduced the new day.

"Mornin', Nick! You look like like shit."

Grabbing the coffee, Nick returned the greeting with a "Hrmph", sitting up straighter in the chair and reaching for the alarm to shut it off. Bringing the piping hot coffee to his mouth, his desire for the the brew fought a brief battle with the nerve endings of his lips warning him that taking a sip was probably not a good idea. Coffee lost out this time and he shook his head slightly to clear the cobwebs out, answering Sae with what mustered for a smile at this time in the morning.

"Yeah. I guess I do. Morning, Sae."

Even as Nick and Sae shared an apartment, they saw surprisingly little of each other these days. For almost as long as he could remember Sae had been the only constant in Nick's life,

taking care of him; providing for them, loving him and guiding him. Six years older than her brother, and only thirteen when their parents died around ten years ago, it was still a mystery to Nick how Sae had managed to navigate habgov bureaucracy and not only keep the lease on the apartment, but also to stay on as Nick's primary caregiver on record. It would certainly have involved some of her more arcane hacking skills, but even today he had no idea how she had been able to manipulate habgov central without detection. It was really only after Nick's sixteenth birthday last year that they had stopped flinching every time the doorbell rang.

For the last few years, Sae had been working at least two jobs at a time, and sometimes more. In the beginning it was to make the payments on the apartment and to feed the two of them; Nick had expected her to take it more easy after he got a job and a steady income, but for some strange reason that had only seemed to trigger her into jumping into even more projects.

Where Nick loved spending hours in his observation bubble or to spend time in the bar with friends, he could not remember Sae ever not doing something and being productive, in some fashion or other. Filling every minute of every day, even when eating at their small shared dinner table she would fill the time studying or reading some research paper on data mining or AI or finite state machines.

"So, what's gotten your airtube in a twist?" she suddenly asked; surprising Nick. Normally she would be heading out the door at this point. Her way of always bouncing from one activity to another seemed almost like running away from standing still, and he couldn't remember the last time she had stuck around after waking him up in the morning.

Sipping at the now drinkable coffee, Nick gathered his thoughts. "Remember I sent you a message yesterday?", he said and continued. "Some Truly Weird Shit is going on".

As Sae gestured for Nick to continue, he began... "So, you know about that laser receiver array..."

--

One of Sae's most eerie personality traits was her ability to go into this weird trance mode when she needed to concentrate. It was doubly weird because of her way of bouncing off the walls when she was in motion between places and activities, but if she was listening to something interesting, the world would quieten around her. As Nick told the story, there were none of the interruptions or sidetracks he remembered from yesterday when he was telling Rashi. Rather, her focus on him and his story was total, excluding everything else in the universe for the twenty minutes it took him to tell it. It also helped that she was a complete genius with computers and that he did not have to explain any technical details to her. Explaining about data protocols to Sae would be like telling an auditor about the AI Moratorium Edict.

As he finished his story, he expected her to take a couple of minutes to digest everything, but she immediately spoke up, surprising him.

"Show me that data"; in her deliberate and insistent voice, it was a directive not giving Nick much choice whether to comply or not. Of course, he thought, mentally slapping himself around. He must have been completely exhausted yesterday. Instead of trying to do a full semester course on protocol decoding in one night, he could just have reached out to Sae for a few pointers.

"Sure", he replied, and gave a few commands to his mindpal. Connecting to Sae's mindpal and sharing his raw analysis, as well as giving her read access to the data he had stored on the qube, he sat back to wait. As he watched her, Sae's eyes got the slightly glassy and bright look of someone working on the mindpal desktop, and he noticed the tendons in her fingers twitching as she mentally typed commands. Nick used the interlude to finish his coffee and to grab some biscuits for breakfast.

"Right", he heard her murmuring to herself. And he caught something about dictionary, state machines and quite clearly "Aha! Is this just a ... Turing tape!?".

Refilling both their coffees and sitting back in the chair, he did a quick query to check what a Turing tape was.

Named after a British mathematician who lived somewhere around 200 years ago, a Turing tape was apparently a component of something called a Turing machine, and a Turing machine was again a theoretical computing machine. Reading on, Nick learned that a Turing machine used a theoretically infinite string of symbols called a tape to manipulate the machine into doing calculations. With a sufficiently long tape, the calculations could actually represent any algorithm in the Universe!

Some minutes later, Nick was exploring some more esoteric variants of the Turing machine when Sae's eyes cleared. Sitting up straighter, with a very strange expression on her face, she looked at him.

"Nick. Did you know you are carrying around alien software in your brain?"

Sae was obviously expecting a big reaction, but Nick had already had a day to consider the implications of the signal, and Sae's pointer to Turing machines had just been another brick in his conviction that this was something alien.

Too calmly he responded; "I guess I am. The question is, what is it?"

Taken aback with his composure, Sae was quiet for a few seconds, organizing her thoughts; before responding: "Well, you mentioned the possibility of it being some kind of media file, due to the long repeating sequences. That is certainly a possibility, but I actually think this indicates some type of divider in the code. It's almost like someone put in non-encoding chunks of data to make it clear where the real stuff is. For example, if you disregard the beginning of the file, you actually have a good Gigabyte or so of what looks like a dictionary description, followed by some very strange repetition sequences. It's almost like someone put in an introduction and an index. Then you have a long repeating sequence of the same symbol, followed by another few Gigabytes of what I think is almost certainly a Turing tape encoded message."

Continuing, she added "A Turing tape is a way to code...". Nick held up a hand to interrupt her.

"I actually know all about Turing machines", he said. Noticing her expression he admitted "Well, I actually looked them up while you were reviewing the data. The question is; how do we move from a hypothetical Turing tape with alien symbols to something we can use?"

This time he was appropriately impressed and surprised, as Sae replied; "I've put together a simple virtual machine for you. It's based on some older architecture, but I think it's safer that way. I really don't want to expose whatever this is to newer computer architecture, and I really don't want to give it too much resources. So - I've created a VM with the least processing and the least memory power I can configure. I've also put together a simple Turing machine interpreter, and set it up to read what looks like the basic dictionary and the first coding block of the message. Oh and. This is important, Nick; I've configured it in an isolated environment. I've set up a simple screen and keyboard layout, and restricted all other methods of interaction. Whatever you do, don't permit any network access to the VM. It helps that you've already isolated it to the storage qube, and I've added a basic firewall that should prevent any ...accidental overflow into the mindpal drive.

If my theory is correct, this should work...." she said, and Nick accepted the transfer she was initiating to his mindpal.

With a thought, and an uneasy look at Sae, he loaded and activated the VM. A single Big Red Button, saying "Run" appeared in his vision. Looking up at Sae, he mentally pressed the button, which was replaced instantly by a black screen.

Nothing happened. Then something did.