In the bride's chambers

Cadence
Check
"What is this?" Cadence asked glaring at the knight on the table.

"My response." Check replied flatly. "Do you want a translation? Fine. Call it a calling card. Or a challenge. If you force a fight. Then you will receive a far greater defeat. I promise."

Cadence laughed. "Are you joking? How would YOU be able to defeat me? What Have you planned? A spy in the wedding party?" She laughed.

"Even if I don't. There are other ways to beat you."

Cadence laughed and waved him out.

Turning away, Check called to the changeling. "Come. We have places to be."

"But the princess."

"Has chosen her fate." Check replied as they went down the hallway. Stopping next to a guard, he whispered before concentrating down the hallway. "Once we explain the plan. You'll be safe."

"But what's going to happen?" The changeling asked.

"If I'm right. A magic…" Stopping the corner of a wall he glanced down the path before taking a few steps back. "blast…"

"What is it?"

"The answer." He smirked. With that said he made a mental note of the location before heading down the hall.

Later at Luna's room
Luna sat at her nightstand, looking over reports for her night guard when a knock came from the door. "Let him in." She told the guard that was standing at the door.

With a nod he opened the door revealing Check and a shy looking mare. The two walked in as Luna motioned for the guard to wait outside. Once they were alone, Luna motioned them over. "What's the news?" Shr asked in worry.

Check sighed. "I have good news and bad news." He answered. Good news is I know what we're up against. And we have this young lady to thank."

"I… I'm not much younger than you." She pointed out nervously.

"Noted." Both Check and Luna replied.

"And the bad?" Luna asked fearing the worst.

"An army is preparing to attack the city." Check explained.

"No doubt you have a plan." Luna sighed. "And what of our friend here? I don't believe we met."

"That's where it gets a little complicated. She's the informer that warned you about the attack." Check explained, motioning for the mare to move forward.

"I… I…" the mare bursted into tears. "I betrayed my queen. I told you about the attack because I don't want anyone to get hurt. I'm sorry."

"It's ok child." Luna cooed. "Please, explain what you can."

"My… My kin and I are… changelings." She explained, before wincing back, expecting the princess to erupt. However, after a few moments of silence, the mare looked over shocked to see Luna had a calm expression on her face. "You… you're not mad? Or surprised?"

"Not at all." Luna replied with a smile. "I knew a changeling queen growing up." Closing her eyes she let out a soft laugh. "She taught my sister and I a few spells from her lands." Luna let out a soft sigh at the memory. "You can drop the disguise. You're among friends."

After a few moments the mare dropped her disguise, revealing her true form. "I… I don't want to be cast out."

"Do not fear child." Luna explained. "If needed, I will speak to my sister about finding you a safe place to stay."

"This may be a stretch princess. But… perhaps, she can stay in Ponyville." Check suggested. "I'm certain one of Twilight's friends will be able to give her a place to stay."

Luna thought for a moment. "You may be right." She agreed. "And if the invasion does happen. She'll need something that can keep her safe and let others know she's on our side."

"Other than staying at my side?..." Check thought for a moment. 'Maybe… there's something I can do to increase our chances.'

"What do you need, Check?" Luna asked.

"There's a wall in the lower hallway that is different from the rest. I'd like to see what's inside." He explained.

Luna thought for a moment before nodding. Getting up, Luna moved to the door. "Guard. Go inform two of my sister's guards and one of your comrades to come to the west halls. And bring a med kit to be safe."

"Princess?"

"Check and his assistant will be going into the catacombs." She explained.

"Right away princess." He replied before galloping off.

Turning back to the others, Luna gave a soft smile. "Stay at Check's side and you'll be fine." She explained. "I trust the two of you to protect our subjects and get to the bottom of this threat."

The changeling nodded before taking up a unicorn disguise and pressed against Check. "I will princess. I… I know healing spells… and scanning magic."

"Then you will indeed be of great help to Check." She replied before smiling broadly. "In fact. I think I may have an idea of where you may stay once this threat is taken care of."

A moment later the guards returned. "Princess. We're ready. The passage is open and the hallway is on lock down."

"Good." Check explained, making his way over with a wing over the mare. "Once we arrive. See to it that nopony passes."

"But." Check stopped and turned to the guard in a snap, causing the guard to freeze and stutter. "N… nopony… understood."

At the secret passage
Two guards stood on both ends of the hallway as they approached the door. "Remember what I said." The guard nodded back in understanding as Check, the mare and two guards entered the passage.

"What do you think we'll find in this forgotten maze, sir?" A guard asked.

"The truth. If you don't mind my lady? Would you mind scanning for life?" Check asked.

With a nod her horn lit as Check made sure her horn was out of sight from the guards. "Found her."

"Lead the way." Check replied with a smile as he patted her back.

"Her?" "Are we missing something?"

Author's Note

I wonder how this invasion will turnout. After all. Check seems to be onto something. Do you guys want to see a chapter of what's going on in his head? Maybe a dream sequence?