They entered through a large door, which fell inwards as they approached it. On the other side of the door, the air was thick with a green smog, which obscured their view of the vast hallways of filing cabinets beyond. The rows of cabinets stretch seemingly infinitely upwards and across. Batman ventured forward, while Yin followed closely behind, peering down the hall. They stopped at a junction where a sign pointed to different sections marked alphabetically. Batman followed the signs until he came to a stop before a cabinet marked 'Y'.

"Y for Yin..."

Looking down at the cabinet in question, Yin frowned.

"Somehow, that seems too easy. What if it's a trap-"

But Batman was already reaching for the handle, not hearing her warning. In response, the cabinet came flying open, flinging him across the hall where he came to a crash again another set of cabinets. Yin came over to where he lay wincing, offering out her hand.

"I mean, I did try to warn you".

"It was worth a shot".

Batman looked up, still a bit shaken, grasping her hand and she pulled him up. Both of them glanced over to the open cabinet, filled to the brim with chattering teeth, taunting them. Frustrated, but undeterred, Batman moved away from the giggling cabinet, continuing the search. Yin stopped again, pointing down the opposite end of the hall, where a small desk could be made out in amongst the gloom.

"How about down there? Looks like an information desk."

Batman turned to see what she was pointing at. Between that and the endless cabinets, he couldn't find any better options. The two made their way towards the desk, wary of any more traps. A man sat at the desk, stamping documents, with a bored look on his face. As they approached him, he raised his head slowly.

"That cabinet was marked Y for Yucks actually," he motioned in the direction they'd come from, "You must be looking for the detective." He didn't seem to notice Yin standing next to Batman, who crossed her arms, listening intently.

The man's voice sounded terribly familiar, though it lacked the manic glee of the person Batman associated with it. He took a step forward, getting a closer look at the man. The ordinary looking man didn't share the bleached white makeup, nor the exaggerated features, but Batman could tell clearly that this was who the Joker had been before he'd become the crazed clown.

"You're…"

"The only shadow of his former self left in this crazy place? It's my day job, but all I want is to make people laugh". He rested his head on his arm, with a satisfied smile. Running out of patience, Batman slammed his hands onto the table, causing the man to shrink away from him.

"Where is she?"

"That's top secret! You don't know what he'll do to me!"

Fear crept into the man's face as he pleaded. Yin walked up to Batman, turning towards him.

"Hey, go easy on the guy, he's probably your best chance at finding me."

Batman nodded, but remained firm, though his tone softened slightly.

"Her life depends on it."

The man sighed in defeat.

"You're in the wrong department, you want current schemes, around the corner to your-", before he could finish, he was interrupted by another, more malevolent voice which echoed throughout the room.

"Now what did we discuss about giving away family secrets?"

The floor began to cut away beneath the desk man, the sound causing him to look down in terror. Before he could yelp, the floor fell away, and he tumbled down into a boiling vat of chemicals below. Batman and Yin looked down in horror at what had transpired, watching as something rose out from the depths of the vat. The leering face of the Joker looked up at Batman.

"Water's warm Batman, dive in. Hehahaaa!"

Suddenly, Batman was stricken with an ear-splitting headache, making him grab his head in pain. He felt Yin's presence vanish next to him in that same instant. An image of Yin's face appeared before him, changing into a skull and back again in quick succession. The flashes were gone as quickly as they came, Batman's vision coming back into focus. He looked to his left to see that Yin had returned to his side, gripping her head in pain.

"Well, that was unsettling," she winced, lowering her hands.

Batman felt relieved at the sight of her. Yin's presence seemed to clear his head, though her momentary disappearance troubled him.

"Did you see what I saw just now? he asked.

Yin nodded, "If you mean by the trippy skull vision, then yeah. Really not a good look on me by the way."

Having seen that she was ok, though somewhat shaken, Batman began his search for the 'Current Schemes' department. It didn't take them long to find the place in question, marked by a glowing neon sign and a purple door with a harlequin painted onto it. Batman pushed open the door without any hesitation. Yin could sense his growing impatience. She wanted to say something to reassure him, but Batman was already making his way into the room beyond.

A large jack-in-the-box stood in the middle of the room, almost filling up the entire space. The Joker's gleeful cackles could be heard once again bouncing around the enclosed space.

"Better hurry Batman, Yin's running out of time," the madman taunted him from an unseen place. Batman was getting close to the obscene box, when Yin noticed a hole open up before him. She reached out her hand towards him in warning.

"Lookout!"

She was too late, however, as Batman had already fallen for the trickster's trap, falling down the hole into a slide chute, which ejected him into a mirror at the bottom. He passed right through it into a completely different room, lined with mirrors on all sides. Batman slammed into the ground, grunting in pain. A set of footsteps came towards him. Looking up his eyes met those of Hugo Strange.

"The Batman? How'd you manage to get here?"

A/N: Hope you enjoyed this chapter. Why would Yin be here in Joker's mind you ask? Probably gonna get the answer sooner than you think. ;)