Itachi's gaze fell on their prisoner. "We should make sure to secure him first, though."

Shisui crouched down to relieve the agent of his gear. "He had a flashlight, too. I think it rolled over when I knocked him out."

Itachi looked around and finally found it a few steps away. "I have it." He switched it on. "It is still working."

"Good," Shisui answered and handed Naruto the man's ninja wire.

Naruto looked at him in confusion.

Shisui grinned. "We haven't covered how to tie up people yet, so we might as well use the opportunity to practice. Start by twisting his arms behind his back."

Naruto knelt down and followed his instruction. "Like this?"

"Yes," Shisui agreed. "Now use the wire and wrap it around his wrist."

"Tighter," Itachi corrected him calmly. "Remember, you are securing an enemy operative."

"Make sure not to cut off the blood circulation," Shisui added. "Good, now the feet..."

Shisui leaned down to check over Naruto's work and nodded. "That should be tight enough. Not bad for your first try."

"Indeed," Itachi agreed. He stepped closer and crouched down next to their captive.

Shisui switched his flashlight to his other hand and kept it steadily pointed at the man as Itachi patted down the agent's body with practiced ease.

It was when he reached the man's flank jacket that he found something interesting.

He carefully extracted the item out of the pouch.

It was a key.

"It appears our suspicions were correct," Itachi told his companions and held his discovery up. "This agent was on a mission. The question is, is he really a guard? If yes, what was he guarding, and why was he placed here?"

"What do you mean?" Shisui stopped in his inspection of the key in Itachi's hand to look at him.

"Don't you think it is strange?" Itachi inquired. "Danzo apparently went to great lengths to hide something. But then he places a guard inside a room without an obvious entrance. Why draw attention to something being amiss when anyone stumbling over this place might just have left again - without discovering anything?"

Shisui narrowed his eyes. "Now that you mention it, it is strange. You think it might be a trap?

Itachi inclined his head. "The possibility is there."

"And if it isn't?" Naruto injected and looked between his two friends. "Maybe he wasn't guarding anything, and we just surprised him doing whatever?"

His two older friends sent him approving looks.

"A valid objection," Itachi agreed, finally standing up again. "And a possibility we need to consider, too."

Shisui nodded and rose to his feet.

Naruto sighed and slumped slightly. "That's so troublesome."

Shisui snickered at his word choice, and Itachi smirked slightly.

"It seems you made quite a bit of headway."

Naruto's eyes brightened when he heard the familiar voice next to him. His jiji had returned! The ghost gave his charge a quick once-over and nodded in satisfaction when he could not see any injuries. Naruto jumped up and unconsciously moved closer to the man.

"I have scouted a bit ahead," Tobirama informed him. "The area has changed since the last time I have been here. This tunnel, for example, is entirely new. I believe it is part of Danzo's hideout."

Naruto bristled and shifted slightly to cover his displeased reaction.

"There are quite a few pathways surrounding this area," the Nidaime continued, "At least one leads into this room. The entryway is concealed. Your friends should be able to discern if it is behind a genjutsu or if it has been camouflaged by common means. Before that, however, I suggest you deal with your prisoner."

Naruto looked at the tied-up ROOT operative. "What should we do with him?"

Itachi extended his hand towards his best friend. "Shisui, your prisoner scroll."

Shisui raised his eyebrows. "Why do you think I have one?"

"Because," Itachi answered drily, "I know you were on patrol yesterday and you are always too lazy to empty your pockets."

"Oy! That's not true!" Shisui shot back. "I empty my pockets… Sometimes."

"Of course," Itachi agreed amicably. "It only took you three months to unpack your desert equipment after you had returned from Suna. Now stop squabbling and get on to it."

"Yes, taicho," Shisui answered sarcastically and tossed the scroll at Itachi.

Itachi caught it with a smirk and sealed the ROOT agent away. "Now that we have taken care of this, we should focus on finding the key's counterpart." He paused, before adding, "It is truly inconvenient that we do not have enough flashlights."

"I'll just stick to one of you," Naruto answered. "You see more clearly, anyway."

Itachi inclined his head. "Very well."

Shisui and Itachi spent the next few minutes systematically scanning the room while Tobirama used the opportunity to instruct Naruto on camouflage techniques.

"If you want to hide something in plain sight, you need to make sure that it blends in with your environment. A tree is best hidden inside a forest. Before you start hiding your tree, however, you need to consider its accessibility. The more often you need to visit it, the easier the access to it should be. If you need to visit it every day, it would be very inconvenient if you needed several hours just to reach it."

Naruto nodded inconspicuously. It made sense. He always made sure his instant ramen was well-hidden but easily accessible, too.

Or at least, he tried to.

Because for some reason, his jiji always found the hiding places and ended up confiscating his cups.

Tobirama's hand landed heavily on his shoulder, and Naruto's wandering mind immediately refocused on the current task.

The ghost gave him a pointed look, making it clear that he was completely aware of Naruto's short inattentiveness. "Focus, child," he chided softly and gestured at the wall in front of them. "Look around. Try to apply my example to your current situation and remember your opponent is a shinobi."

Naruto nodded.

It was Itachi who finally found it.

The keyhole might have not been hidden under a genjutsu, but the Sharingan's sight was still way sharper than that of a normal human.

That was why he had easily seen that something was not quite right with a certain part of the floor.

There was a small hole at the conjunction between the ground and the wall; its sharp, clear form carved too cleanly into the stone to be natural.

Itachi signaled his friends over. "Shisui, Naruto. I have found it."

His companions immediately joined him, and four pairs of eyes surveyed the small hole.

"Cool." Naruto grinned. "So, what now?"

Shisui crouched down to inspect it.

"It looks like some kind of mechanism. I believe that turning the key will trigger it. We should see if we can't spot more irregularities around this."

Next to Naruto, Tobirama suddenly stiffened. "I can feel a chakra signature behind this wall. It is approaching us quickly."

Naruto reacted immediately. "Someone is coming. We need to hide, now. "

The two Uchiha threw him confused looks, but the urgency in his voice must have been convincing enough for them to heed his warning.

His friends immediately grabbed him and retreated into the shadows.

Just in time to see the wall they had just inspected sink down with a loud grinding sound, giving birth to another tunnel.

A shadow stepped out of it, paused at the entry, and looked around.

It seemed like it was searching for something.

Or someone.

Finding the room in front of it empty, the shadowed figure turned towards the tunnel.

A flashlight was switched on and Naruto could see the silhouette of a masked woman.

The Root agent stepped closer to the spot the four were hiding in. "Tiger? Is that you? You know that Danzo-sama wants–"

Naruto never found out what Danzo wanted, because Itachi had moved the moment the agent had come into view. Red was the last thing she saw before she slumped down.

"That was easy," Shisui commented lightly and nudged the downed body with his foot. "Oh look, we got a third flashlight."

Itachi rolled his eyes at his friend's antics.

The woman quickly joined her colleague in the prisoner scroll and the four congregated around the opened tunnel.

Tobirama put a hand on Naruto's shoulder. "I shall go ahead again. If I come across any hostiles, I shall warn you – or deal with it myself. Be careful and listen to your friends. They have proven to be quite competent."

Naruto watched his jiji vanish in the darkness of the tunnel. He did not like being separated from him for too long. Naruto really wished they had some way to communicate over the distance; just to make sure that Tobirama was safe.

"Well, that answers the question about it being a trap or not," Shisui's voice cut into his musings.

"Yes," Itachi agreed. "But we should still be cautious. There might be more ROOT operatives around."

Shisui nodded at Itachi. "So, who goes first? You or me?"

Suddenly feeling very mischievous, Naruto interjected from behind. "Age before beauty."

Itachi smirked and patted Shisui on his shoulder. "You heard him."

Shisui fixed Naruto with a mock-indignant glare and whirled around to throw a beseeching look at Itachi. "You realize this makes Naruto more beautiful than both of us, do you?"

Itachi raised an eyebrow. "I am handsome, not beautiful. Besides, I am going to bring up the rear, so it won't matter, anyway."

Shisui groaned. "You two are impossible!" he complained, "Fine. Let's see if we can't bring some light to the dark." He picked up the flashlight again and moved the light cone into the darkened corridor.

"That was a terrible pun," Itachi commented flatly behind him.

"No comments from the peanut gallery!"

The tunnel was different from the one before. The ground was less uneven, and Naruto did not have to worry so much about stumbling over loose rocks anymore.

It was also more spacious than the previous one and wide enough for them to walk next to each other.

It also meant that they had more ground to cover now.

In response, Itachi and Shisui had shifted slightly in their positions. The three of them were now walking offset in a diagonal line instead of a chain; the two older shinobi careful to keep the youngest between them.

Their new formation also had the advantage of allowing them better sight because their line of vision was now unobstructed.

It had been quite challenging to walk in a single line when only the first person had been in possession of a flashlight. Now that everyone had their own light source, moving about was a lot easier.

Naruto's gaze wandered over the grey stone surrounding them. Somehow it seemed more solid and smooth than the kind of stone he had seen in the previous room.

"The walls are made out of syenite," Itachi told Naruto quietly when he saw the young boy curiously eyeing the stone wall. "It is very durable and therefore often used in construction. The fact that someone has made the effort to smoothen the stone proves that this tunnel is intended for a more permanent use."

"It's probably part of an underground base," Shisui chimed in. "We should be more careful from now on. So, no loud and passionate singing," he added jokingly.

Itachi threw a flat look at the back of his head. "Sound advice from the one whose singing could be weaponized. I suggest you disregard your own advice once we make enemy contact. - On a second thought, please don't. You might disenable your allies, too."

Shisui bristled, and Naruto's shoulders shook in silent laughter.

"Joke aside," Itachi added, serious again. "It would be best if we refrained from speaking for the time being."

Shisui frowned. "How are we supposed to communicate, then? Naruto does not know the sign language."

"Um, actually," Naruto interjected, drawing his friends' attention, "I do."

For a moment, the two Uchiha just stared at him, then Shisui sighed. "I don't even know why I am surprised anymore," he muttered. "Fine. Signing from now on."

Itachi nodded once, and they moved on.

The area slowly became brighter, and they saw a soft light flickering in front of them.

They stopped almost at the same time.

Shisui exchanged a serious look with Itachi.

'Scout?' Itachi signed.

Shisui nodded once and turned towards Naruto, making the sign for clone.

Naruto nodded once and immediately made a henged copy of himself.

Itachi nodded in approval when the rat scurried around the corner.

There was a long moment of silence until Naruto's clone dispelled and he gave his friends the all-clear sign, followed by the signs for 'permission' and 'speech'.

Shisui and Itachi nodded in confirmation, and Naruto immediately reported his clone's findings. "The tunnel ends at a door. A metal one. It looks like one of those you'd find in a hospital. There was nobody around."

His friends exchanged a serious look.

"A door that looks like one in a hospital, huh?" Shisui repeated grimly. "Do you think what I think, Itachi?"

"Yes," Itachi answered, "It sounds like we might have found an underground laboratory."

"Do you think it could be one of Orochimaru's?" Shisui looked rather pensive.

Itachi narrowed his eyes. "Perhaps. But if this were the case, the implications would be rather grave."

Shisui nodded. "Well, there's only one way to find out, right?"

"Indeed."

A/N

...and the adventure continues. What will they discover? Find out in the next episode of The Three Shinobi - The Root of the Problem.

Itachi: "That was a terrible pun."

Author: "No comments from the peanut gallery!"

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