"Knock Knock Knock"

Twilight looked up from her book, puzzled. Project Starburst shouldn't be back from the lake yet, and she had asked Applejack to take Rainbow's place guarding the door. There shouldn't be any visitors right now. She went to the door, opening it and looking out. "Um, hello?"

"Princess, good morning. My name is Cardinal Rule, and I've come with some information you might find interesting." the curly haired Earth Pony Stallion at the door smiled. "I believe that your town has been infiltrated, and I'd like to help you stop the perpetrators."

Twilight took in the stranger, who seemed to be quite in earnest. Of course, it was entirely possible that this was a trap, and she considered several paths that this interaction could take. He was an Earth Pony, and she had a considerable amount of magic, experience, and Applejack right nearby. She stepped back, showing him in. "Alright, Cardinal. Why don't you tell me what's going on?"

"We're not too far off now." Rainbow Dash said, leading the other four ponies down the path. Once she had filled Applejack in on what was going on, Rainbow had seemed to be quite eager to get into some action at last. "This bend up ahead is where we found the weather ponies."

Angel was not far from Rainbow Dash, looking around at the area. It was strange anything would be based out of here, it wasn't central to anything at all. The lake was on the other side of town from the Everfree Forest, and a good distance away from any large roads. It would be a good hiding place, for sure, but there was no real way to launch an attack of any sort on Ponyville. It would have made sense to stay in the mountains, instead of coming down to this location.

So, the question came down to the unusual sightings. They had radiated out from around this location, forming a distinct pattern. Angel continued to ponder this as they arrived at the lake, and Rainbow Dash turned to them expectantly.

"So what do you all think?" she asked, Greymane taking a few steps forward to check out the lake.

"There doesn't seem to be anything unusual about the lake itself..." he glanced up at the sky, shaking his head. "Or the weather." He and the others gave their surroundings a good look over; a few scattered trees, a meandering path up into the foothills of the nearby mountains through a flowerbed.

"I agree. This place seems to be fairly...quiet..." Cloud Prism had started, before spotting a figure walking down the same path they had just arrived by. He turned, seeing two more coming down past the flowerbed. "I get the feeling we're about to find out what's going on."

"A crescent shape...starting in the mountains and centralizing here..." Angel's brow was furrowed as she mumbled to herself, picturing the map in her head. The way the dots had connected, the order of the sightings.

"Um, hello." Spiral Dream waved, the figure from the path turning out to be a pegasus; the ones from the foothills were a pair of unicorns. "We were just wondering what was going on down here. Seems to be a lot of activity..."

A lot of activity, focused around the lake and spreading out-Angels eyes widened and she turned to the others. "It's an invasion!" she cried out. Rainbow Dash looked over at her.

"What do you mean, an invasion? Who's invading?" she asked, already on guard.

"That is the question, isn't it?" A familiar voice rang out. All eyes turned to the path again, as a fourth figure had joined the others: Golden Luck. "That was really impressive of you, Angel Grace. I suspected you might figure out what was going on."

"What is going on?" Cloud Prism asked, still glancing around at the ponies currently surrounding them.

Golden Luck smiled...and burst into flames. Flames which soon cleared, revealing her true nature. Black Chitin, blue eyes, and holes in her legs, mane and tail.

"Changeling!" Rainbow Dash exclaimed, already leaping forward. Golden Luck held up a hoof, shaking her head.

"I wouldn't do that, if I were you." she remarked coolly, motioning at the group with her head. Spiral Dream and Angel Grace were facing down a unicorn, who had conjured up some rope and already had Angel Grace mostly bound up. The other unicorn was facing Cloud and Greymane. "We're all going to come in quietly, and no one's going to get hurt, okay? There's someone eager to meet you all, but she has to attend to one small matter of business, first."

Rainbow looked between Golden Luck and Spiral Dream, who was putting up a valiant effort of her own. She was even trying to use her hypnosis magic to entrance the unicorn into letting her go. Unfortunately, it didn't seem like it was taking effect fast enough, and the pegasus by Golden Luck had joined the second unicorn.

"Rainbow...Cloud..." Greymane said with a heavy sigh. "We've lost this one. It's not going to do any good for us to get hurt."

Golden Luck smiled, nodding her head slowly. "Very good, Greymane. As long as you all do as you're told, everything will be fine." she took some of the rope from one of the unicorns, helping to tie up the ponies. "Now, come on, everyone. We're all waiting for you."

"We?" Cloud Prism asked, as they were led towards the mountains. "Who is we?"

Golden Luck glanced back, as she resumed her old form. "You'll see, soon enough. This has been in the planning stages for long enough, a few more hours won't hurt..."

Author's Note

In case you're wondering what "Golden Luck" looks like:

Kudos to whoever guessed she was a Changeling.
Double Kudos if you know why none of the mind control stuff works on her.