Mr. Robot is a show built on hacks. The mother of all hacks serves as the big cliffhanger at the end of the show's first season, and nearly every plot development leading up to it was nudged along by some kind of exploit. It’s rare to get through an episode without at least one digital intrusion, often drawn from real life. Each week, we'll be running throughMr. Robot's C Y B E R activities — who got hacked, why, and how much magic would be required to make them actually work.

* * * S P O I L E R S F O L L O W * * *

We’re so close to finding out what the hell is going on! Dear God I can taste it!

In the meantime, there’s a lot of stuff that’s still up in the air. Darlene and Cisco may or may not be dead. Tyrell’s walking around and saying things, but he could just be an alter, a dream or some kind of hacker ghost. We also got to see Whiterose’s gaming den, which is pretty cool. I have to believe she could afford something nicer than a Commodore 64, but I suppose she’s as nostalgic as the rest of us.

FOLLOW THE RED WHEELBARROW

After last week’s Lost-style "find the missing clue" shot, we finally found out what Mr. Robot was looking for in Elliott’s apartment. Tyrell left him a secret menu code, written on a Red Wheelbarrow BBQ menu! We spend the next few minutes following the code, which eventually leads us to a phone number, which spits back out a speech-to-text robot reading of an address where cab is waiting.

It’s a classic trail of clues, the kind of thing Mr. Robot usually forgoes in favor of malware and social engineering. But it’s also a staple of the genre, so it’s good to see the show take a crack at it.

Find the missing clue!

The trail starts with a series of numbers, each standing in for a letter. This is the simplest kind of code there is: a substitution cipher. Mr. Robot types it in through the standard encoding — A=1, B=2, and so on — but it’s just garbled text, so he has to try something else.

Then things get interesting. He turns to the ROT-13 cipher, favored by Usenetters as a way to hide spoiler text and anything else they want disguised. ROT-13 works by shifting everything forward 13 letters — A turns into N, B turns into O, etc. — and because 13 letters is exactly half the alphabet, you can run it twice and end up right back where you started. That makes it easy to run as a Usenet command, which made it very popular in the early chatroom days!

Of course, they couldn’t make it too easy, so that just gets him another set of instructions, complete with references to obscure but easily Googleable number sets. Here’s what ROT-13 gets them, with some judiciously added punctuation:

The perrin pages will help you find your calling, but don’t be duped. Cut down the woods they be erdos.

Why do any of this

As it turns out, there’s another set of numbers within the menu, and all Mr. Robot has to do is remove any Perrin or Erdos-Woods numbers. Luckily, the fine folks at the Online Encyclopedia of Integer Sequences have put both sets of numbers online. (Seriously, you’re doing God’s work out there.) They’re mathematically interesting in ways I do not understand!

Once all the numbers have been taken out, you’re left with seven numbers that just happen to work as a phone number. What a trick!

WHY DO ANY OF THIS AT ALL, THOUGH

That’s a good question! It doesn’t seem much easier than, say, dropping in a URL / password combination. In security theory, the big thing you worry about is interception, which seems like a pretty serious concern for this setup. If someone — say Agent Dom DiPierro, for instance — managed to pick up the menu while it was waiting in Elliot’s apartment, it would be entirely possible for her to go through the same steps as Mr. Robot. And since Elliot’s very possibly been under federal surveillance during much of this time, that’s a very real concern!

So… why do it this way? The one other factor that occurs to me is Elloit’s very bad memory. Mr. Robot seems to know what’s going on pretty well, but if you’re in Tyrell’s shoes, there’s no guarantee that Mr. Robot will be the one picking up the message rather than Elliot. Even if he is, maybe he has the same memory problem?

There are still a lot of unanswered questions, including whether Tyrell is real, what happened to Mobley and Trenton, and whether capitalism can survive the ever-accelerating extraction of natural resources at the expense of the very ecosystems that provide our most basic needs. But hopefully at least one of those questions will be answered by next week’s episode! And even though we’ve seen our last Digital After Show, I’ll be back here next week to talk about all the hacks that pop up in the last episode. Let me know if there’s anything else you want to know about!

Disclosure: NBC Universal, owner of USA Network, is an investor in Vox Media, The Verge’s parent company. Additionally, we are an independent editorial partner in the Mr. Robot Digital After Show hosted by The Verge.