On the way down in the elevator — this time it was Brack’s — Charlie made a list on his notepad of the clues and questions they had.

“You have the hunter’s gleam in your eye, Master Hitchcock,” said Brack. “Do I detect that you have solved the puzzle?”

“He’d better have solved it,” muttered Tyler.

Charlie grinned and told Brack, “Well, I’ve solved at least part of it.”

Brack leaned in to look at Charlie’s list. “So you have juggled all your clues and evidence together,” he said, “and that’s why you are traveling to the basement?”

“We always end up in the basement,” said Tyler.

“But the mystery was already solved upstairs on the ninth floor,” said Charlie. “Down here, we’ll find out who’s behind the mystery.”

The elevator stopped and the doors slid open.

“Good luck,” said Brack. “I hope your solution turns tragedy into comedy.”

As the elevator doors closed behind them, Tyler looked down at Charlie and said, “That guy is always saying weird stuff.”

Weird, but full of clues, thought Charlie. Tragedy and comedy?

“I think he’s pretty smart,” Charlie said, raising an eyebrow. “Anyway, where should we go?”

Tyler shrugged and pointed. “This way,” he said. “Follow the pipes.”

Long metal ducts snaked across the ceilings. As they walked deeper into the basement, more and more of the ducts appeared from different directions.

The ducts connected and joined together, forming even bigger pipes, all running in the same direction. All of the pipes passed through a wall near a door labeled BOILER ROOM in thick, dark letters.

When the boys opened the heavy orange metal door, Tyler and Charlie were met by a blast of thick, warm air.

All the ducts entered this room. Half of them flowed into the dozen metal boilers. The boilers heated air. Then the air was carried by the other ducts to the vents on all the hotel’s floors.

“If someone could be heard through that vent upstairs,” whispered Tyler, “then they must be somewhere in this room. They have to be.”

Then Charlie gasped. He grabbed Tyler’s arm. “Look! Over there!” he said.

A man’s shadow covered one of the room’s cement walls. His hands fluttered up and down in a strange way, as if he were brushing aside spider webs. Or as if he were a magician casting a spell.

His hands stopped.

“Mister Ken,” they heard him say. Then the man’s shadow disappeared.