They arrive at Cadmus Labs to find the fire, as promised, largely under control by a fire crew. 

Two men in labcoats are leaning out of a window on the upper floor and calling for help, flames clearly visible in the room behind them.

"Stay calm!" one of the firemen shouts up to them. "We will get you out!"

Just as the four heroes arrive, something explodes, propelling the two men out of the window and sending them flying through the air. 

Kid Flash is the first to react. 

Dashing forward, he runs up the side of the building in a blur of speed and grabs the men by their collars, arresting their fall. His momentum lets him heft them both up onto the roof, and he manages to catch the lip of the window as he himself falls back down, ending up dangling by his hands.

The firemen are delighted.

"It's what's-his-name! Flash Boy!" 

"Kid Flash!" he yells back, annoyed.

"Why is that so hard?"

The others, moving a little slower, arrive in time to see Kid Flash's partly-successful attempt at rescue. 

Robin chuckles. "Sooo smooth." 

"Does he always have to run ahead?" Aqualad mutters.

"We need a plan," he continues, louder. "We - Robin?" 

Robin is already gone, racing in and swinging off a beam using his grappling hook. 

He joins Kid Flash at the window and helps him climb inside the building. 

Fortissima brings her flute to her lips and starts playing a fire-suppression spell. It probably won't put the flames out altogether, with this big a fire, but it should at least make them more manageable.

Aqualad nods in approval, and runs forward to help out himself. Since Fortissima is dealing with the fire, it shouldn't endanger anyone if he borrows the water from the hoses for a minute.

"I need to borrow that!" he warns the firemen, before unsheathing the hilts strapped to his back. In place of blades, each hilt brings with it a stream of water, which he sends out to connect with the water from the hoses, bringing it all under his control. Mentally shaping it into a platform beneath his feet, he rides a column of water up to the roof, where he collects the frightened scientists and takes them gently back down to the ground. 

"Need a ride?" he asks Fortissima. 

She nods, not interrupting her music to speak.

He motions for her to join him on the watery platform, and takes them up to join the other two in the second floor. 

Once they're both safely inside, he relinquishes control of the water so the firemen can get back to work. 

"Appreciate the help," he snarks at Robin and Kid Flash. 

The latter are both investigating the room, Robin typing away at a computer and Kid Flash peering in cupboards. 

"You handled it!" Robin counters, looking away from the screen for a second to grin at Aqualad.

"Besides, we're here to investigate. Poetic justice, remember?" 

"So what've you found so far?"

"Not much," Robin admits, still tapping away at the keyboard.

The glow from the screen is almost the only light in the room, giving an ominous blue cast to his face. 

"I - huh?" He looks up at Aqualad, who's standing in the corridor just outside the room.

Aqualad looks he's seen a ghost. He's standing stock-still, staring at something at the end of the corridor. 

"There was something in the - " 

Kid Flash is abruptly standing next to him, following his gaze to the closed elevator doors.

"Elevators should be locked down..." 

"What's wrong, I don't see anything--"

Robin pushes past them, frowning, to get a better look at the elevator itself.

"This is wrong..."

He scans the doors with his wrist computer, looking up the make and model.

"Thought so. This is a high-speed express elevator. It doesn't belong in a two-story building!" 

"Neither does what I saw." Aqualad still looks a little spooked.

Stepping up to the elevator, he wedges his fingers in between the doors and shoves them open, metal creaking in protest. 

He looks down.

And down.

The elevator shaft is several times deeper than the height of the building above ground, disappearing down into darkness below them.

"That's why they need an express elevator," Robin breathes. 

"So Batman was right to be suspicious, clearly."

"And I was right to assume so." 

Robin sights up at the ceiling of the lift-shaft, only a few feet above their heads, and fires a grappling hook at the exact centre. He jumps down the shaft, playing out the grappling line to control his descent. 

Aqualad gestures for Fortissima to go next.

She could slide down Robin's rope, which looks easily strong enough to hold all four of them, never mind just her and Robin, or make her own way down by magic. 

Yeah she was never good enough at those slidey-poles on the playground as a kid for going down the grappling hook line to be a good idea, magic it is.

Aqualad jumps on the line himself and slides down to join Robin, followed by Kid Flash. 

"I'm at the end of my rope!" Robin has stopped at what the signs on the walls declare to be sub-level 26. They're nowhere near the bottom of the shaft. 

He swings over to the side of the shaft and lands next to the door, again followed by the other two boys.

"Bypassing security..." More tapping on the wrist computer. "There!"