It had been another rough day in hut 8.

Alan knew the math was correct. But when elegant theories clashed with the reality of poorly made cogs and technicians that wouldn’t follow simple instructions, things went wrong.

He knew they were close. It would work. But you could never completely chase away the doubts. What if they failed? Would not the time and money be better spent on planes and bombs that would do good today, rather than a pile of wires and parts that might help tomorrow?

But it was four in the morning, and quiet, and after a long day being distracted by others, Turing was at his best; working alone and in silence.

Behind him there was an unfamiliar buzzing sound. The buzzing became louder, with a few snaps and crackles. There was the unmistakable smell of ozone, like after a thunderstorm.

Alan turned and looked. Floating in mid air was a disjointed, but animated, bust of a man.

Coping with the distractions and complaints that came from the long hours of concentration had become second nature to Alan. He was used to the nausea, and the headaches, and being tired. But the hallucinations were something new. Lacking any alternative, and always keen to see where a new experience would take him, he decided to play along.

“Good morning,” Alan said.

“Hello,” the bust responded. “Am I speaking to Alan Turing?”

“Yes. May I ask who, or what, you are?”

“My name is Elon Musk. I have been sent here from a secret project in the year 2016. We have developed the capacity to examine history, and return back in time to influence things to our favour. I am here to help you continue your work.”

“I don’t really need your help,” said Alan. “I know how important this work is. Being able to intercept the Naval Enigma will give us an enormous advantage.”

“I know,” Elon replied. “But for some reason you abandon it all in the next few days. The impact to us is enormous. We think it might change things if you knew what could result if you continue your work.”

Elon continued, “if you continue your work, it becomes the basis for the development of general purpose computers. Computing becomes commonplace, and revolutionizes society.”

Alan smiled. “If true, I guess that would be encouraging. I suppose by your time there are hundreds of computers.”

“Billions,” Musk replied. “They are now small, and they can communicate with each other. Almost everyone carries one with them all the time.”

“Amazing. Imagine the wonderful things you would be able to do. You could be learning all the time. You would build remarkable machines that handle all the drudgery of life.”

A slight frown crossed Elon’s face. “Well,” he replied, “what we mostly do with them is play Pokémon Go.”

“What,” Alan asked, “is a Pokémon Go?”

“It’s a game. It creates make-believe animals. Then it gives you hints so that you can go and find them.”

Alan looked confused. “You mean like hide and seek?”

“Oh no!” Elon was enthusiastic in his response. “There is much more to it than that. There are PokéStops, where you buy eggs and Poké Balls and potions!”

“Sorry,” Alan asked, “you said buy? Didn’t you mean to say give? These things are artifacts; they would cost nothing to produce.”

“No, people pay money to buy them.”

Alan scowled. “Are you telling me that 70 years from now small computers, that derive directly from the work I am doing here today, will be used to induce people to pay money to play hide and seek?”

Musk paused, then replied. “You make it sound silly saying it like that.”

“I believe,” Turing replied, “you would find it silly whatever way you say it.”

Both men sat in silence.

Finally, Elon spoke. “So has my time here been helpful?”

“Oh yes. It is now very clear what I must do.”

“Good. I am afraid I have run out of time.”

There was a gentle pop as the apparition disappeared.

Alan sat in silence. Then he began his work.

First, he burned all his notes.

Then after making sure the Bombe was well soaked in kerosene, he set fire to the hut.