"Where is the third crystal?" Kai asked Luna as the library wall cracked wider.
"That is the problem," Luna's voice whispered in his mind. "The third crystal is not in a place. It is in a person."
"What do you mean?" Kai asked, running toward a back exit as books crashed around him.
"The third crystal chose to live inside someone's heart instead of becoming an object. It has been hiding there for over a hundred years. But to get the crystal, that person would have to..." Luna's voice faded.
"Would have to what?" Kai pressed.
"Die," Luna said sadly. "The crystal can only be removed when its host dies. That is why the third crystal is the most dangerous to obtain."
Kai felt sick to his stomach. "I can't kill someone just to get their crystal."
"I know," Luna said. "That is why you are worthy to carry us. A true hero would never harm an innocent person."
The wall behind them exploded, and Shadow creatures poured into the library. Kai ran faster, clutching both crystals in his hand. The creatures were getting closer.
"There has to be another way," Kai said. "Tell me more about the person with the third crystal."
"Her name is Maya Chen. She is seventeen years old, just like you. She lives in the floating city of New Haven in dimension seven. The crystal chose her because she has the purest heart of anyone in all the dimensions."
Kai reached a small door at the back of the library. When he touched it with the crystals, it opened into a bright tunnel filled with swirling colors.
"This is a dimensional portal," Luna explained. "It will take us to New Haven. But Kai, you must know something else about Maya."
"What?" Kai asked as he stepped into the portal.
"She does not know the crystal is inside her. She thinks she is just a normal girl. But because of the crystal, she has special abilities. She can heal people with her touch, and she can see into their souls to know if they are good or evil."
The portal spun around Kai, and colors flashed past his eyes. He felt like he was flying through space.
"How long has she had the crystal?" Kai asked.
"Since she was born. Her mother was the previous host. When her mother died in childbirth, the crystal moved into Maya's heart to keep her alive. Maya would have died as a baby without it."
Kai felt even more troubled. "So if I take the crystal, Maya will die?"
"Not necessarily," Luna said. "There might be a way to transfer the crystal without killing her. But it would be very dangerous for both of you."
The portal began to slow down. Through the swirling colors, Kai could see a beautiful city floating in the clouds. Buildings made of white stone and glass sparkled in the sunlight.
"Welcome to New Haven," Luna said. "The most peaceful place in all the dimensions. But I fear that peace will not last long. The Shadow will follow us here soon."
As Kai stepped out of the portal onto a platform made of crystal, he looked around at the floating city. Somewhere in this place was Maya Chen, a girl who held the key to saving all worlds but who might have to sacrifice her life to do it.
"I will find another way," Kai promised. "I will save Maya and get the third crystal. There has to be a solution that doesn't require anyone to die."