[Transcriber's Note: This etext was produced from Scientific Detective Monthly April 1930. Extensive research did not uncover any evidence that the U.S. copyright on this publication was renewed.] _A thousand alarms are pouring into Police Headquarters! The Invisible Master broods over the city! Who is He? We defy any reader to guess the secret! Even the editorial staff of SCIENTIFIC DETECTIVE MONTHLY was astounded at the conclusion of this scientific yarn. Write and tell us if you were able to foretell the ending._…
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