As soon as the Solar Guard appeared in front of Applejack, she knew something was wrong. At the words "assassination attempt", Applejack sprinted off towards the castle, and was soon joined by Rainbow, Pinkie, Fluttershy, and Rarity, and four other Solar Guards. Blasting through the castle door, they fell into a pile at the sight of Twilight, alive and well.

"Hey, girls." Twilight said, before being crushed by a hug from each of her friends.

"You're okay! We totally need to have a PARTY!" Pinkie yelled. "Oh, wait. We still got those meanies to deal with!"

"Don't worry about the assassins." Twilight said. "My new guardian took care of them."

"What?" Applejack asked.

"Lemme start from the beginning." Twilight said. She recounted the events of the previous hour, and by the end, even Rainbow was slightly scared at the deeds of the Sentinel.

"He took them all out?" Rainbow said, shocked.

"Yes. Quite easily." Twilight said, "Listen, we're all heading to Canterlot. The Sentinel should be back anytime now…"

"I have returned, Element of Magic."

Each pony turned to see the Sentinel walk in. At the sight of him, Pinkie began to stammer.

"S...S...SO COOL!" she yelled. The Sentinel gave her an inquisitive look.

"I am fine in terms of body temperature, Element of Laughter. Is this some kind of humor?"

"Nah!" she said. "Just saying you're AWESOME!"

The Sentinel bowed in response.

"Princess, the train is awaiting us." The Sentinel said.

"Alright, let's go." Twilight said. As the Sentinel and the Solar Guards headed to the Train Station, Rainbow looked in slight fright at the Sentinel.

"If Twilight trusts you…" she said quietly. "Then I do too."

============

As the Elements, escorted by the Solar Guards and the Sentinel, arrived at the Train Station, Twilight noticed the train had a guard posted to each window.

"For your protection." The Sentinel said to Twilight, when he noticed her inquisitive look. Twilight led the Elements into a separate car, and soon, the train was moving. The Sentinel sat down and removed his helmet, revealing his face to the other Elements.

"Wow." was all the Elements could say. The Sentinel nodded and closed his eyes, beginning to meditate.

"Twi, I think we should get some actual sleep." Applejack said. "I think we're safe, at least for now."

"Sentinel?" Twilight said.

"I shall watch you." the Sentinel replied. As he, Twilight, and Spike walked into a sleeping car, Applejack looked over at Rainbow.

"Think they'll be alright?"

Rainbow sighed.

"From what I've seen...yes."

==========================

As the train arrived at Canterlot, Twilight woke up to the Sentinel already awake.

"Princess, we have arrived." he said.

"Thank you, Sentinel." She replied. As she woke a grumpy Spike, the Sentinel walked out to see several Solar Guard awaiting them. Sentinel stood in front of the door, blocking their path until Twilight walked past him, followed by Spike.

"Princess, this way." The Guard leader said. The Sentinel took the point position, and as the elements joined them, the guards and Sentinel led the way through the streets. Occasionally, a passing citizen would glance and stare, or whisper at the sight of the Sentinel. Twilight looked at him, though he seemed to be calm and at peace.

"Princess Twilight, Princess Celestia is expecting you." A guard said upon arriving at the Castle. Twilight thanked them, and as they departed, The Sentinel nodded and escorted Twilight, Spike, and the Elements to a secured Dining room. As the seven of them sat down, Celestia and Luna looked at her with relief.

"Was your trip safe?" Celestia asked.

"Yes." Twilight replied. "No disturbances. Sentinel kept watch the whole night."

"Good. The guards have not managed to get any of the assassins to speak of the conspiracy. All still refuse to talk. Amadeus Blueblood has also gone missing, and we suspect she is part of the conspiracy."

"It is just logic." Sentinel said. "Adequate search forces must be rallied in order to find her."

"We shall do so." Luna said. "Though, finding how far this conspiracy stretches is our first priority."

"If I may…" Sentinel said. "Our first priority should be to protect the Element of Magic. She is still in danger. Until the threat on her life has been lifted, it would not be wise to let our guard down."

"A fair point." Luna said.

"So it is." Sentinel said. "However, as Canterlot is rife with the schemes of nobles, and Ponyville is no longer safe, we must find a safe haven for the Element of Magic."

"You are not wrong." Luna said. "The Crystal Empire, perhaps? Shining Armor and Cadance would be glad to see you."

"Sure." Twilight said. "You hungry, Sentinel?"

"I require no sustenance." Sentinel replied. "As a spirit of Harmony, I need no refreshment, but the thought is appreciated."

"Alright." Twilight said.

The Sentinel nodded in response. A Solar Guard walked in, bearing a letter addressed to Celestia. Celestia took it, and the guard walked out. Celestia sighed upon finishing.

"We have a new foe to contend with. Amadeus has an alicorn child."

"What?" Luna and Twilight said at the same time, full of shock.

"Yes. Majesty is an alicorn. And Amadeus has set himself on the path to rebuilding Unicornia. They already have an army of mercenaries at their back."

"Then we must leave right away." Sentinel said.

"Agreed." Twilight said. Then, the ground shook and the castle rumbled. Sentinel got up, drew his sword, and advanced to the window.

"We are too late. We must leave NOW." he said, opening the curtain. In the streets below, pandemonium was nigh. Mercenaries bearing the flag of a unicorn's horn and a star advanced, battling the Solar and Lunar guard as they went. Twilight gasped at the sight of the chaos in the streets.

Sentinel said nothing as he, Twilight, Celestia, and Luna rushed out, and were soon joined by a platoon of mixed Solar and Lunar Guards.

"Get a shield around the palace!" Sentinel said. "If this castle falls, the land falls with it!"

As the Guards sealed the doors with powerful magic, which Celestia and Luna reinforced with their own magic, the Sentinel escorted Twilight to the postern gate.

===============

Outside, the mercenaries attempted to blast through the castle gate, with no success. As the Solar Guard and Lunar Guards retreated beyond the gates, Amadeus Blueblood watched from afar, with an alicorn teen by her side.

"Lord Blueblood, the sisters have reinforced the gate and placed a shield around the palace. We're not getting in anytime soon." a mercenary reported.

"No matter. We control the city. That's enough to rally other nations to our cause." Amadeus said.

"What of the other assassins? Were they not captured?" Majesty asked.

"They're done for." Amadeus said. "Let us consolidate our grip on the commoners."

===============

At the postern gate, Twilight was ushered into a subterranean tunnel, lined with stone support beams and torches.

"What is this?" Twilight asked Celestia.

"A tunnel built during the early days of Canterlot, when we were still at war." Celestia replied. "It was mainly used as an escape route for sieges. Now, this tunnel will take us to a safe location where we can travel to the Empire."

As they walked, the Sentinel never left Twilight's side, his hand on his sword. After thirty minutes, they arrived at an exit to the surface. Twilight's eyes took in a small lodge built into a mountainside forest.

"How far away did we go?" Twilight asked upon seeing Canterlot in the far distance.

"Quite a distance, Twilight." Celestia said. "That tunnel was more than an escape route. It was also enchanted to take whoever walked along it to wherever they wished. It appears to our enemies to have collapsed, since it could only be used once."

"Wow." Twilight said. "What's with the house?"

"It's one of our old hunting lodges left over from unification." Luna said. "We vacationed here a few times."

As they walked inside, the guards set up positions, while Twilight took a look around. Celestia set to writing a letter to Cadance, and Luna started sending messages to various cities, asking for help. The Sentinel followed Twilight, and eventually they ended up at a small garden. Twilight sat down on a bench, and the Sentinel did so as well.

"Are you alright, Element of Magic?" he asked.

"It just seems so...terrifying." she said. "Amadeus once compared me to Queen Chrysalis. I didn't know I was so hated that they would try to kill me while I slept!"

"It is disturbing. However, there is still light in the dark." Sentinel said. "I know who can help us."

"Who?" Twilight asked.

"The Tree of Harmony." Sentinel said. "When it was formed during the days of unification, a great army was set upon the path to its destruction by a powerful General. When the General attempted to claim the Tree's power, the Tree sensed his malice, but also his bravery, his genius in the art of war. He was not cursed to die, as others have, but he and his army were sent to a realm unseen, where they would wait until called."

"Why is this important?" Twilight asked.

"Because this army is not of the living." Sentinel said. "The General and his forces were cursed to an existence of living sleep, bound to the tree's service. When the tree calls, they are forced to answer. This army, if released from the Tree's power, would prove to be a powerful ally in our fight against our foes."

"Sentinel, what was the name of this General?" Twilight.

Sentinel looked her in the eye.

"His name is Scipio. And he possesses the army we need to defeat our foes."

"Where can we find him?" Twilight asked.

"The Tree of Harmony sealed Scipio in a cavern to the north from whence he came, in a monument to all his sins."  

"Then...that would place him near the Empire." Twilight said.

"Indeed. However, Scipio was known to be a proud general. Convincing him will be a difficult task."

"How do you know this?" Twilight asked.

"Because…" Sentinel said.

"I fought for him, many years ago."