THE YEAR IS 1422. King Henry the Fifth of England, hero of Agincourt and conqueror of France, is dead. His son and heir is a ten month-old baby. The land is ruled by a council of quarreling nobles, the country is uncertain and the throne is shaky. A mysterious secret society called The Black Flame threatens the very foundations of the law, the Church, and the kingdom itself in a deep and terrible conspiracy of murder, treason, sorcery and devil worship. On the windswept northern coast of England stand Burnstow Abbey and the convent of St. Regula, headquarters for the Black Flame and the setting for deeds of debauchery and depravity of a kind to shock even the hardened fifteenth century. Royal agents sent to investigate vanish or wash up on the shore dead. Graves are opened and bodies taken for blasphemous and terrifying occult rites. Young women enter the convent of St. Regula and never come out. A young novice at the abbey, Arthur Fitzroy, the bastard son of the late King Henry, is found horribly murdered in an obscene parody of the crucifixion. The regents must take action, and so they send in the Middle Ages' most har-boiled detective: Sir Thomas Clave, the Black Knight. Murdering monks, poisoning prioresses, scheming royal uncles, back street assassins, a mad alchemist, a beautiful and dangerous Queen of the Witches, the Black Knight cuts his way through them all to discover the truth and prevent the final horror set for All Hallows' Eve.