The Devil's Chord
From Tardis Wiki, the free Doctor Who reference
The Devil's Chord was a tritone musical chord, which was banned by the Catholic Church "in mediaeval times" due to a belief that it would "allow the Devil to enter the room". The Lost Chord capable of summoning Maestro incorporated the Devil's Chord. (TV: The Devil's Chord [+]Loading...["The Devil's Chord (TV story)"])
