The next morning Alex headed straight for Tobias' shop. He couldn't wait to tell Tobiasand Christopherwhat he'd figured out. Christopher's movi ng wall was nothing compared to Alex's ghostly discovery.

Tobias and Christopher were already in the shop when Alex got there. Music that sounded like a hymn from church blared out of the open door. Tobias was singing along, pushing a dust mop. Alex spotted Christopher dusting the counter.

"Hey!" Alex shouted. But the music was so loud, Tobias didn't even look up. "I've solved the mystery!" Alex yelled.

Christopher looked up from the counter and waved at Alex.

Alex ran over to Tobias and tapped him on the shoulder. "Turn it down!" he yelled, motioning to the radio.

Tobias turned the music down. "Hello, Alex. That buyer I told you about is coming back for another look at the shop. That's why Christopher and I "

"But you may not have to sell," Alex said. "Tobias, I know who's trying to run you out of here!"

"What?" Tobias asked.

"Who?" asked Christopher.

"Ghosts!" said Alex.

"Braawk! Ghosts!" said the parakeet. It landed on Alex's shoulder and hid its head inside Alex's shirt.

"I heard them last night when I locked up," Alex explained. Alex stopped talking. He thought he heard something above them. "There!" he said. "Did you hear that?"

Tobias, Christopher, and Alex stared at one another in silence. "I don't hear anything, Alex," Tobias said.

"Wait," Alex begged.

Then it happened. Bang! It was different from the night beforemore like a kick on the ceiling. Bang, bang, BANG!

"See?" Alex said. "Ghosts in your ceiling!"

The sound repeated itselflouder, angrier.

"It's coming from upstairs," Christopher said.

"The last owner said the upstairs was closed off long ago," Tobias said. "I don't think there's a way to get up there."

The parakeet flew off Alex's shoulder. Then it raced back, landed on Alex, and pecked his cheek.

"Ow!" Alex said. "Stop it, parakeet!"

But the bird pecked again. In its beak, it held a long, gold thread.

"What's this?" Alex asked, taking it from the parakeet's beak .

"I'm not sure," said Tobias. He took the string and stared at it. "I don't know why, but it reminds me of something."

The bird flew off and came back with a bigger piece of gold string.

"Looks like he got it from behind your counter, Tobias," Christopher said.

"That's it!" shouted Tobias, racing behind his counter. "There's been a length of gold cord hanging from the ceiling since I bought the shop. I never took the time to climb up there to find out what it was."

Tobias pull ed a thick, gold cord behind his counter. Something on the side wall gave a creak. As they watched, the whole shelf slid to the side!

"That's the shelf in my photograph!" Christopher cried. "I knew it moved!"

Bang! Bang! BANG! The noise above them grew louder and more demanding than ever.

Christopher, Alex, and Tobias ran to the moving shelf. It had slid to the side against the wall. Where the shelf had stood, there was now an arched doorway.

"It's a secret passage, Tobias!" said Chr istopher. Inside the arched entrance, a cement stairway led up. "Come on, Alex!" said Christopher.

Alex didn't want to go up those stairs and face the ghosts of Tobias' shop. But what else could he do? He said a quick prayer, thinking Tobias must be rubbing off on him.

"Here I come!" Alex said, and he followed Christopher up the flight of stairs.

At the top of the stairs was a wooden door. Christopher nudged the door with his foot. It opened a few inches.

BANG! BANG! BANG! The kicks were coming from behind the door. And another noise: "Uhmmm! Uhmmm!"

Alex helped Christopher shove the door the rest of the way open. With all his might, Alex threw himself against the door. It gave way and Alex sailed into the attic room. He didn't stop until his feet hit something lying on the floor. Alex lost his balance. Down he fell, face first, onto the dusty attic floor.

Alex rolled over and looked back to see what horrible creature had tripped him. There, feet to feet with him, sat Kor ina!