Windy City Mystery by Gertrude Chandler Warner

suggested.
    That was a possibility. Comfortable chairs and couches lined the inner lobby. He could read the paper and chat with Willard.
    The doors slid open. The children hurried out. They glanced around. No one was sitting on the chairs or couches.
    The Aldens looked beyond to the outer lobby. Then they saw Grandfather. Off in a corner, he was talking to someone — a man who carried a raincoat and a broad-brimmed hat.
    â€œThere he is!” Benny said, darting ahead.
    Henry caught him. “Wait, Benny,” he said. “Let’s see what we can find out.” He put a finger to his lips, a signal for his sisters and brother to be quiet.
    They crept to the wall between the two rooms and pressed themselves against it. One of the doors was propped open. Still, it was difficult to hear Grandfather’s words over the voices of the other people in the outer lobby. They did hear the tone; it sounded as if the two men were having a disagreement.
    Henry motioned for the others to follow. He went through the doors. Then he stopped short. “Why, Grandfather!” he said, pretending to be surprised. “We were just looking for you.”
    Mr. Alden’s face turned red and his eyes opened wide. He was genuinely surprised. He opened his mouth to speak, but nothing came out.
    The other man stepped forward. He held out his hand. “I’m Jacob Piper,” he said. “You must be the very special grandchildren I’ve heard so much about.”
    The children shook his hand. They all said, “It’s nice to meet you.”
    Something about the man seemed familiar.
    Henry glanced at the raincoat and hat Mr. Piper carried. “Didn’t we see you here earlier?” he asked. “Talking to Willard?”
    Mr. Piper looked at Mr. Alden, then back at the children. He didn’t respond. Instead, he said, “I want to take you out to dinner. I’ve been trying to persuade your grandfather.”

    Mr. Alden recovered his voice. “I told Cob you were probably too tired. After all, you’ve had a busy day.”
    Relief flooded the younger Aldens. So that’s what the two men had been talking about.
    â€œI’m never too tired to eat,” Benny piped up.
    Everyone laughed.
    â€œSo you’ll come?” Mr. Piper said. He sounded pleased.
    â€œWe’ll have to clean up and change,” Mr. Alden said.
    Mr. Piper turned to Benny. “Can you wait that long?”
    â€œI think so.” Benny sounded very serious — and uncertain.
    Mr. Piper laughed. “Good,” he said. “Meet you in an hour.” He put on his hat and turned to leave. “Remember: X marks the spot,” he said as he went out the door.
    That seemed a strange thing to say.
    â€œX marks what spot?” Benny asked.
    â€œWe’ll find out,” Mr. Alden said. “Cob is fond of riddles.”
    The younger Aldens were ready before their grandfather.
    In the living room, Henry said, “Mr. Piper is the man we saw earlier — the man in the raincoat.”
    Jessie nodded. “I thought so, too, Henry. But when you asked him, he didn’t answer.”
    â€œDidn’t you say there was something striped sticking out of his pocket, Henry?” Violet asked.
    â€œYes. A railroad cap — the kind the man with the mustache wore.”
    â€œI didn’t see anything like that,” Benny said.
    â€œMr. Piper was carrying the raincoat,” Henry responded. “It was all folded over. You couldn’t see his pockets.” He sighed. “But I was on the wrong track. He’s not the man with the mustache.”
    Jessie sat down at the table. “Let’s look over the clues again,” she said.
    They listed what they knew. The first clue had been given to them by Willard. The second was picked up outside the Water Tower. The third was at the Art Institute on the student bulletin board. Chad gave them that one. The fourth and final clue