First of all, setting:
The story starts off during an overcast fall evening, after the events of Twilight's Kingdom, Part 2. The thirteen guests arrive at the manor before six, and the story all takes in place in the manor from there. The manor is fairly large, with a foyer that has two curved staircases running on either side and an ornate chandelier, a fully equipped kitchen, dining room that seats up to twenty guests, parlor with billiards table and small library, and six master suites on the first floor.

The guest list is as follows:
Twilight Sparkle: A studious young mare, she has studied under Celestia for her whole life. But what would she be willing to do to impress her mentor?
Cherry Jubilee: An entrepreneur from Dodge Junction, Cherry has fallen upon hard times with a recent drought. What would she be willing to do to keep afloat?
Bulk Biceps: All his life, he has dreamed of one day being in the Equestria Games. But how far will he go to make sure he gets in?
Trenderhoof: An up and coming star in the trendsetting community, Trenderhoof has never been afraid to voice his opinion to a crowd. But how did he get where he is today?
Pinkie Pie: Always one to throw a party, she believes that you can never have enough fun. But how far will she go to make a party off the hook?
Filthy Rich: The owner of Barnyard Bargains, he knows that sometimes you have to get dirty to turn a profit. But how low is he willing to stoop to earn a bloody bit?
Time Turner: The official timekeeper for Ponyville, he is hardly seen outside of sporting events. So what is he hiding?
Fluttershy: Known as a friend to all animals, most people believe she'd never hurt a living soul. But is she holding back a dark secret?
Granny Smith: One of the oldest ponies in town, Granny Smith has seen ponies come and go time and time again. But is someone assisting them to the other side?
Lyra Heartstrings: Known for playing the harp, Lyra has sung many love songs to her marefriend, Bon-Bon. But is her passion an instrument of murder?
Thunderlane: Infamously lazy, Thunderlane is surprisingly well off for a pony who's in charge of handling rainclouds. How does he keep aloft?
Rarity: A rising fashion star, Rarity creates some of the most beautiful dresses in Equestria. But is her rise to fame stained crimson?
Cheerilee: Considered the best teacher in Ponyville, Cheerilee knows how to handle a tough crowd. But does she have the heart to commit murder?

Well, since we already have enough writers lined up to keep this story going until at least Christmas, I have started on the prologue to the story. If I can keep my current rate of work up, I should have it published in the very near future. For now, here's a sneak peek:

Within the depths of the Everfree Forest, a brown stallion nervously hurried toward a mysterious destination. A storm was approaching on the horizon, sending brisk gusts of wind whirling through the branches hanging overhead. He stopped in his tracks, briefly looked around to make sure no one was watching, and took a piece of parchment out of his bag.

He carefully unfolded the paper and set it on the ground. It was unsigned, and was written in a barely legible scrawl. The message itself was fairly simple, giving nothing but a time to arrive and a set of directions. He honestly would have ignored it if it weren't for the fact that the destination was in the heart of the Everfree Forest.

The prologue is finally complete! I will submit the story once I've completed cover art for it.

Guys, good news! The prologue to the story is being published today. I'll provide a link once it's approved, so keep your eyes opened!

Update: a new portion has been added to the prologue. The dinner portion of the evening has been added to the prologue, so I highly recommend rereading it if you've already read it.. Also, DR_LaZer2000 has decided to move back in the order, so LoneUnicornWriter will be doing the first chapter now. Here's the updated order:
1. LoneUnicornWriter
2. Thak
3. SudokuBrony
4. Andulin
5. Yoshi89
6. DR_LaZer2000
7. Interlogue- trombrony98

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Lyra Heartstrings: Known for playing the harp, Lyra has sung many love songs to her marefriend, Lyra. But is her passion an instrument of murder?

lolwut

I'm pretty sure you meant Bon Bon.