While Luffy, Usopp, and Zoro went down the stairs, Sanji stayed behind and held back the Trader from stopping them.
"I'll catch up as soon as I beat the shit out of this damn bastard," he called after them.
"Okay!" Luffy called over his shoulder.
The sound of kicking grew fainter as Luffy went down, Zoro following and Usopp clinging to Zoro's shirt.
Eventually they reached the bottom, where another door awaited. Luffy immediately pushed it open and stepped inside.
The room was lit by several torches on the walls. By this light, everyone could see that the room was mostly empty except for one important detail: There were five children, four girls and one boy, chained to the wall and wearing dirty rags. All of them looked forlorn and empty, simply staring at the ground.
Zoro and Usopp came in behind Luffy and stared at the scene. "This is how slaves are treated!?" Usopp whispered in shock.
Two of the girls looked up and stared at the pirates as if waiting for something. When no one moved, they looked back down at the ground.
Sanji came down the stairs at last. "Hey," he said, "I took care of him. What's—"
He saw the room and froze. "That bastard," he growled. "Now I wish I had kicked him harder."
Luffy, without saying a word, turned and ran back up the stairs.
"Where's he going?" Usopp whimpered, staring after him.
Zoro and Sanji shrugged. Sanji approached one of the girls. "Hey, pretty lady," he said softly. "My name's Sanji. What's yours?"
The girl, who couldn't have been more than 15, flinched, lowered her eyes, and murmured "Vithya, sir."
Sanji smiled and reached out a hand. Vithya flinched again, but all Sanji did was pat her head. "You're going to be okay," he said softly.
She seemed very surprised. As Usopp followed Sanji's example and went to talk to another prisoner, there was the sound of running and Luffy came down the stairs, holding a handful of keys.
"I found these in that guy's desk," he explained. "Some of them probably unlock the cuffs, right?"
"Good thinking," Zoro said, surprised. He grabbed a few keys, strode over to the boy, and started trying them out. None of them unlocked the cuffs, so he tossed the keys to Sanji, who snatched them and started testing them out on Vithya's cuffs. A moment later there were two clicks and the cuffs fell away. Vithya slowly lowered her arms and rubbed her wrists.
"Here," Sanji called to Usopp, tossing him the other keys. Usopp fumbled, caught them, and started testing them out on the cuffs. None of them worked, so he tossed them back to Luffy, who had already approached the third girl. He started trying out the keys on her cuffs and got one of them to work. Like Vithya, the girl—who had told Usopp that her name was Maureen—lowered her arms and rubbed her wrists.
Soon the rest were released as well. They didn't seem to know what to do; all of them just stared at the pirates.
"Well, come on already," Zoro said. "We're getting out of here."
"Excuse me, sir," said one of the girls timidly. "Are you taking all of us?"
"Yeah," Zoro said. "Right, Luffy?"
Luffy nodded.
The boy helped Maureen up and then bowed in the pirates' general direction. "We will be good for you, masters," he said quietly.
"Masters?" Usopp said, confused.
Sanji flicked his cigarette to the ground and stomped on it to put the flame out. "Listen, kid, we're not here to buy you. We're setting you free."
The boy looked up nervously, clearly confused.
"You don't have to be slaves anymore," Usopp said.
The girl that the boy had helped up said softly "I'm sorry, masters, is that a joke?"
"We're not joking," Luffy said. "And we're not your masters."
"Hang on," Zoro said. "Hey, kid, hold still."
The girl flinched, but closed her eyes and did what she was told. There was a slash and a clink; when she nervously opened her eyes, she found that the chains around her legs were broken.
Zoro did the same for the others. They looked at him in awe.
Luffy turned to go up the stairs. "C'mon, everyone!" he called down. "Let's go!"
Usopp, Sanji, and Zoro guided the kids to and up the stairs. They came into the upper room and passed the Trader, who was lying beaten, bruised, and unconscious on the floor. Vithya began sobbing in relief and Sanji held her to comfort her.
Luffy was flipping through the book that the Trader had showed them earlier. "Hey," he said to the kids, shoving the book at them and pointing at the picture of young Princess Erika. "Do you guys know if this girl was ever down there with you?"
The kids looked at the picture. "I . . . I think so, sir," said the boy softly. "But . . . will you please go further in the book?"
Luffy started flipping through pages until the boy put a hand on one page. It showed a picture of a young woman who was clearly the same girl, only at least nine or ten years older.
"This lady was here a few weeks ago," he said quietly. "She said that she'd been a slave for ten years. I liked her and I was sad when she was bought again."
Usopp leaned over and tore the page out of the book. "Thanks, kid," he said cheerfully.
"Okay, Luffy," Sanji said. "What do we do with the kids?"
The children looked nervous again, as if expecting punishment.
"Calm down," Zoro said. "We won't hurt you."
They looked up at him in admiration and clung to his legs.
"I dunno," Luffy said. "But we should get them out of this place, right? How about we take them on the ship with us for now?"
"Fine, but they can't stay the night," Sanji said. "We won't have enough food or beds."
"Okay, you heard him," Usopp said to the kids. "We're gonna take you on our ship and we're gonna get you help, okay?"
They looked down, unsure of what to say or do.
"Let's go," Luffy said, marching out the door. Usopp, Sanji, and Zoro followed, the children still clinging to Zoro's legs.
By the way, the Trader's name is Steve.