A Dr. Edward Levison Mystery
When a string of bank vault break-ins occurs in Jacksonville, Florida, the local police are baffled. The vaults are of the latest model, protected by double combinations and time locks, and supposedly impregnable, yet the cracksman didn't resort to either explosives or metal cutting tools. With the authorities at a loss, it falls to Dr. Edward Lester to solve the mystery based on the slenderest thread of a clue.