Although he is only ten years old, Leo Walker is not curious about his surroundings like other boys. He is more assertive, let alone composed. Leo gets along with his parents. They want him to live and let live.

One Thursday afternoon, Leo and his dad, Tod, were on their way home from the library. They came across Nadine's house. Tod stopped to look. "It must be hard for this family," he said. They turned to leave. As Leo gives the house one more look, singing crept up.

"Dad, I heard something."

"It's only birds, son."

"No, it came from there," Leo pointed.

"Let's get home. Your mom made dinner." Mr. Walker laid a hand on his son's head.

At home, Leo's mom, Gina, told them about the house. "That belongs to the Clark family." Leo saw that the name surprised Tod.

"Clark? As in Jimmy Clark, the former postman?" he asked.

"Yes."

"What happened to him," Leo inquired.

"He died of influenza 5 years ago," his mom replied.

"Oh, poor Donna," Tod said, "she must be heartbroken."

"The strangest thing is I haven't seen her after that."

"Neither do I," Tod agreed. Leo sucked every detail as his parents chattered themselves away.

"Hey, Mom," Leo called.

"Yes, Leo?"

"Do the Clarks have any kids?"

"I believe so. Maybe one."

"Can I be excused, please?"

"Sure."Leo left the table. His parents continued on a conversation without him.

He went to his room. Leo remembers the Clarks. He has seen Mr. Clark bringing the mail every day. So, when he did not see him the day he was sick, he was concerned. Mrs. Clark, on the other hand, seemed to be private when she was seen. Leo knew better than to trouble her. Even so, her disappearance was something rather extreme.

The singing keeps ringing in his ears. "If Mr. Clark is dead and Mrs. Clark is nowhere to be found," he thought, "then, who did I hear?" Leo opened the window. He pondered until he came up an idea.