The moon hung low over Gotham City, casting long, eerie shadows over the streets. Batman moved silently through the night, his keen eyes scanning the landscape from his vantage point on a rooftop. The Bat Signal had summoned him, but instead of Commissioner Gordon, Batgirl had been waiting.

"Batman," Batgirl called, her voice tinged with urgency. "We need to talk. It's about The Joker."

Batman narrowed his eyes. Barbara's demeanor seemed off, but he couldn't quite place it. What was more obvious was that her Batgirl costume had changed. Her cowl was the same. But instead of the purple jumpsuit she used to wear, she wore a lavender silk leotard with matching tights, her usual yellow utility belt around her waist, and pink ballet slippers."What is it, Batgirl?"

She glanced around nervously before speaking. "I have information that The Joker is planning something big. He's set up a trap for us at the old amusement park. We need to stop him before he hurts anyone."

Batman nodded. His instincts on high alert. "Let's go." He wanted to ask her about her change in costume but didn't. He had made subtle changes to his costume from time to time.

The journey to the abandoned amusement park was swift and silent, the tension palpable between them. Batman thought that her new costume belonged to a dancer, not a crime fighter.

The park, once filled with joy and laughter, now stood as a haunting relic of the past, its rides rusted and decaying, shadows dancing eerily in the flickering light.

As they approached the entrance, Batgirl hesitated, then turned to Batman. "This way," she said, leading him deeper into the park.

Batman followed, his senses tingling with unease. They wound through the twisted paths, past broken rides and eerie funhouses, until they reached the heart of the park: the fun house.

Batgirl stopped, her back to Batman. "He's inside," she said softly, her voice almost mechanical.

Batman reached out to her, concern etched on his face. "Batgirl, are you alright?"

Before she could answer, the curtains on the walls fell away exposing mirrors. The music, warped and distorted, filled the hall of mirrors. Images of The Joker emerged in every mirror, his face twisted into a maniacal grin.

"Welcome, Batsy!" The Joker cackled, stepping into the light. "So glad you could join our little party. And thank you, my dear Batgirl, for bringing him here."

Batgirl turned to face Batman, her eyes glazed and unfocused. It was then that Batman realized the horrifying truth: she was under The Joker's mind control.

"Batgirl, fight it!" Batman urged, stepping towards her. "You don't have to do this."

The Joker's laughter echoed through the park. "Oh, but she does, Batsy. You see, I've given her a little... suggestion. And now, she's mine."

With a swift motion, Batgirl attacked, her movements graceful and deadly. Batman was forced to defend himself, his heart aching at the sight of his ally and friend turned against him.

As they fought, The Joker watched with glee, his laughter ringing out over the din. "Oh, this is delightful! Watching you struggle, knowing you can't bring yourself to hurt her."

Batman dodged a blow and managed to disarm Batgirl, catching her wrist in a firm grip.

"Batgirl, you have to fight it," he said, his voice steady. "You're stronger than this."

For a moment, her eyes flickered with recognition, a spark of the real Barbara Gordon breaking through. But The Joker wasn't done yet. He pulled a remote from his pocket and pressed a button, sending a hypnotic impulse into her ears from a listening device hidden under her cowl.