Old Tapes and Pencils

Nice work. We’ve got to be nearing the end now. A standard missile launch code has… what, 8 digits? And you’ve found 6? There’s only one more tape to decode at my end, in addition to the one I’ve just finished. Here, I’ll play it for you now—it looks like he’s talking about the rockets:

You know the manhole covers I mentioned at the last location? Notice how many there are at these crossroads? That’s because this place is important—the manhole covers mark the fuel lines for the underground missile, and this place is where they all meet.

Did you put your ear to any of them? Try the one with the white symbol on it—you should be able to hear the fuel lines firing up. That hatch—the one with the white symbol—is an access port.

The symbol on it may look strange to you, but that’s because it’s an alien character which means ‘danger’—my last ditch attempt if they should ever find this place, to stop the aliens opening the cover up. If they ever do find our fuel lines, they can trace them back to the rocket itself, blowing it up, or even worse, launching it at…

Sorry, this next part of the tape is ruined. You know how those old cassette tapes used to get—they’d stretch out and then you’d have to wind them back in with a pencil.

It looks from my notes like you need to walk across that bridge. Is there some sort of… round green hatch somewhere on the other side? That’s what it says to look out for. Should be about half a meter high. See if you can find it, then check back in when you have.