Maigret and the Madwoman by Georges Simenon

"I'm relying on you. I trust you."

Maigret knew those words would haunt him to his grave. As the famous inspector stared down at the lifeless body of of the frail old lady, her last words to him kept hammering at his ears: "I'm relying on you. I trust you."

The little old lady had been hanging around Police headquarters for days. She insisted on seeing only her hero, Maigret. Finally, she confronted the Inspector and patiently told her story. Somebody was trying to do her harm. She didn't know who, and she didn't know why.

Maigret promised to call on her as soon as he could find a free moment. Maigret felt partially responsible; how could he not. This was going to be a special case. He would find the killer if it was the last thing he ever did!