The room was colder now, the kind of chill that didn't come from poor insulation—it came from the unknown. Concrete walls closed in around them as they stood at the edge of the open trapdoor, peering down into darkness.

Nell crossed her arms loosely, casting a glance toward the suspect zip-tied in the corner. "I swear, if there's a murder dungeon down there, I'm putting in for a transfer to Cyber Crimes."

Callen smirked faintly, crouching to get a better look at the ladder. "You've said that before. Still here."

"Yeah, well," she said, stepping beside him, lowering her voice slightly, "you make fieldwork just barely interesting enough to stay."

He gave her a quick side glance, something just shy of a grin tugging at the corner of his mouth. "I try."

Without another word, he tapped his comm.

"Sam, we've got one in custody, east wing. Found a trapdoor. There's a level below. We're heading down."

Sam's voice crackled back.

"I'm coming in from the south. You need backup?"

"Not yet. But tell Kensi and Deeks to keep eyes on the front—if anyone bolts, that's where they'll go."

Kensi came through next, clear and confident.

"Already moving. We've got the front covered. No one's getting past us."

Deeks added in the background, "Unless they bribe us with tacos. Then all bets are off."

Callen clicked his comm off and turned back to Nell, who was already watching him with raised brows.

"You sure you're not just looking for excuses to take me into sketchy basements?" she asked, head tilted.

"I mean," he said, stepping onto the ladder with a calmness she recognized, "if I was trying to impress you, it'd be a rooftop with a view. This is just bad luck."

"Right," she said, smirking as she followed. "Next time, try candles and less mildew." she quipped, eliciting a soft chuckle from Callen.

They dropped into the shadows, boots landing softly on concrete below. The air was stale, the kind of stillness that made it feel like no one had breathed down here in years.

Nell adjusted her grip on her weapon. "Okay, this place officially creeps me out."

Callen swept his flashlight ahead. The beam cut across walls lined with old piping, the concrete damp with condensation. "You're doing great. Very poised. Hardly any trembling."

Nell shot him a look. "I'm trembling with anticipation."

He raised an eyebrow, glancing back at her. "For what?"

She leaned in just slightly. "For you to finally admit I'm more fun than Sam."

That made him chuckle—low and unexpected, a break in the tension for half a second. "You might be."

She grinned. "Oh, I definitely am."

Then—a sharp noise ahead. Metal against concrete.

Both froze instantly. The humor drained from the air like someone flipped a switch. Callen stepped in front of her without a word, the shift so natural she almost didn't catch it—almost.

But she did.

That protective instinct, subtle but solid. It didn't feel like overkill. It felt like trust. Like he wanted her with him, but not before him.

His voice dropped. "Movement. Left corridor."

They crept forward, back to back, lights low, weapons raised.

Callen's voice returned to the comm.

"We've got movement below, sub-level east wing."

Sam's voice was calm but quick.

"Copy. Almost to your location. Keep eyes sharp."

Nell leaned toward him slightly, her voice just for Callen this time. "If we get shot at down here, I'm calling dibs on your leather jacket for a trauma blanket."

He gave a quiet breath of amusement. "Deal."

They turned the next corner—lights sweeping the corridor, finding no one. But they could feel it. The presence. The pressure. Someone was close.

And they weren't done yet.