The title Hamlet: A New Source, A New Reading, is an accurate description of the intention and contents of the book. A Discovery and playne Declaration of sundry subtill practises of the HOLY INQUISITION of Spaine (London, 1568) by Reginaldus Gonsalvius Montanus inspires the atmosphere of espionage that constitutes acts II and III of Shakespeare’s masterpiece, as proven by conspicuous parallelisms between the two texts. This atmosphere in turn suggests a new reading of the play, especially of the prince’s “delay” in carrying out his father’s command. The delay is caused by Hamlet’s decision to test by natural means the credibility of the supernatural revelation received from the ghost, and for that purpose he uses the arts of the Inquisition as described by Reginaldus Montanus. As is well known, the Reynaldo of the definitive text of the play was called Montano in the “bad quarto,” and his first mission is to “inquire” about the Danes that are in Paris, and particularly about Laertes’ conduct. As soon as Hamlet realizes in the play-within-a-play that the “ghost was honest”, he does not hesitate for a moment to claim the throne that his uncle had tyrannically usurped. The sparing of Claudius while he is at prayer in III.3 receives a plausible explanation in this book on the basis of the theological background of the scene.