Complex sentence: The existence of the substance has been a sacred secret of the Castaka's for many generations, until an accident happens and the secret must be sacrificed to save the life of Othon von Salza, the son-in-law of Baron Berard of Castaka.
Split into simpler sentences: The existence of the substance has been a sacred secret of the Castaka's for many generations. Until an accident happens and the secret must be sacrificed to save the life of Othon von Salza, the son-in-law of Baron Berard of Castaka.