A monster of evil came to the nation’s capital. A green-masked ambassador from Hell’s own legation, followed by a horrible horde versed in the poison torments of the Far East! Even the police who sought to trap him did not guess the ghastliness of his real motive. That remained for Secret Agent “X” to discover as he prowled through a dark and sinister labyrinth of Washington espionage. Who is the Green Mask? Is he a spy – or worse? What enemy nation does he serve? Can the Man of Mystery unmask this traitor-or will he himself be exposed by a searing light that will destroy his shadowy career?
