"I must say, this is very exciting," Professor Hotchkiss said. "Over a dozen people have contacted me about the Listener, recently. You're the first one to visit me in person!"

"A dozen people?" Bruce asked.

"Yes, and they all seem very reluctant to tell me why," Professor Hotchkiss said. "What has brought about this sudden interest in a crystal skull?"

"I can't say for certain," Bruce said.

"Ah, but I can easily guess," Professor Hotchkiss said. "There is an obvious explanation for all this secrecy. The Listener has appeared on the black market. Am I right?"

She was. A crystal skull known as the Listener was the centerpiece of an upcoming black market auction. Both the Joker and Ra's Al-Ghul had expressed interest in acquiring it, hence Batman's urgent need to find out more.

"I'll be honest with you," Bruce said, lying through his teeth. "A friend of mine came to me last week, claiming he could get his hands on a genuine crystal skull, if I gave him a small fortune. My friend has a somewhat...shady reputation. I too suspected the black market was involved. I wanted to make sure the deal was legitimate, before giving him any money."

"A wise plan," Professor Hotchkiss said. "Well, I'll tell you what I told the others. Each of the crystal skulls is said to have a unique power. One grants immortality, another, the ability to fly. The Listener is called that, because it improves your ability to listen."

"It gives you better hearing?" Bruce asked.

"Oh no, of course not," Professor Hotchkiss said. "Nothing so common or mundane as that! It gives you the ability to listen to other people's thoughts."

"You mean it gives you psychic powers?" Bruce asked.

"Exactly," Hotchkiss said. "The last known account of it comes from a Mr. Richard Topham, in 1928. He touched the crystal skull at a pawn shop, and for a full week, he was able to hear everyone's thoughts. According to Topham's records, it was an unpleasant experience. Nobody had any nice thoughts, whenever he was around.

"Naturally, once he learned what the crystal skull did, Topham rushed back to the store to purchase it," Hotchkiss said. "And that's where the trail goes cold. The pawn shop owner claimed he sold it to a jeweler named Waddell. Waddell claims he never received it. No one knows what really happened, and it's likely that Topham made the whole thing up to boost his reputation."

"His reputation?" Bruce asked.

"Topham went on to open a school for the development of paranormal powers," Hotchkiss said. "It wasn't very successful, and once he was shown to be a complete fraud, he was run out of town. You can see why someone like that would lie about having a telepathic crystal skull."

"Interesting," Bruce said. "If it's been lost for over 70 years, there's no way to be certain that it's the same skull that Topham had."

"Exactly what I told the other people who asked," Professor Hotchkiss said. "Some of them were less than happy to hear that. The truth always seems to disappoint someone, you know."

"Do you think one of them could have robbed you?" Bruce asked.

"What, as an act of revenge?" Hotchkiss asked. "Well, I did have a student slash the tires of my car after I flunked them four times, but this situation hardly calls for such dramatics. Besides, the thief stole one of my French artifacts, totally unrelated to the crystal skulls."

"Was it related to the Queen's Tower?" Bruce asked.

"Yes! I believe so!" Hotchkiss said. "Rumor has it that the lost diaries of Marie Antoinette are locked inside that tower. Unfortunately, much like the Listener, it hasn't been seen in decades. I asked Baxter at the front desk, and he refused to give me a tour. I tried looking myself, but I couldn't even find the entrance!"

"But what was your stolen artifact?" Bruce asked. "An antique key?"

"A medallion," Professor Hotchkiss said. "I have a video of it, if you'd like to see."

"If it's not too much trouble," Bruce said, smiling.