Straw Hat Murders

It's tough being being Chief of Homicide when there have been four murders of piano students-all in the same studio apartment! So Huntoon Cambourne knows his job is on the line as he tries to prevent a fifth murder. He's not lacking for clues because there is a cheap straw hat found at the scene of all four murders. And then there's the matter of the killer leaving a $20 gold piece in the alms bucket of a deaf and blind mendicant down on the street near the apartment house. But how does the murderer get into the death room when the only opening is a trapdoor that's only reachable by a dangerous 7-foot leap?