Dear Sergeant Merryweather,
Discovered the mystery of the ghostly moaning.
My butt hurts now.
...I mean, thats what I'd kind of like to say, but, since you're my former superior officer, I can't in good conscience do that to you. I would also like to apologize about me using the word 'butt'. I would cross that out, but, it feels like that would trying to deceive you, and, I'm just not gonna do that.
To be honest with you, Sergeant? My first mystery in the dungeons was a dud...
I got Private Upsy Daisy, who was also curious, to help me with it. But, before we could check the deeper dungeons for the source, she told me 'Why don't we just listen to the vent? We can probably figure out what's going on in from there'.
And, so, since the vent was higher up, and flying indoors inside the dungeon isn't allowed-unless its an emergency, of course-we stacked boxes. Then, I got on a few, and she stood on my back. We listened for a good few minutes.
Throughout that time, we came up with various possible answers: Diamond Dogs, Timberwolf Zombies, Diamond Dog zombies, the zombified remains of Charbuck Sheen's acting career, and, finally, my grammy.
...She- She does actually do that a lot, you know. She stands right outside of Canterlot, takes her picnics, and, before barely any time at all has passed, she's moaning about how the cold is affecting her aching back.
Sadly, we finally figured out that none of those answers were the right ones, and the real one was staring us in the face all this time: It was just the wind. Just some cool, possibly cold wind coming in from outside.
Well, I was disappointed, and, after Sergeant Buck surprised me so hard that I lost my balance, and fell on my keister, he made Private Upsy Daisy and I do one hundred wing push ups each.
...Even my wings are sore right now.
But, thats not gonna get me down! There's still at least five more mysteries to solve, and, I know that at least one of them has to be a good one. They won't keep secrets down here forever...
Your Humble Ex-Subordinate,
Private Flash Sentry.