Ahhh, prussic acid, that hallmark of classic Golden Age mysteries. Did lovely Cara Quoyne get a whiff of the bitter almonds as she raised the goblet to her lips? We’ll never know: With a single sip she transported herself to the Hereafter.   At least, that’s the romantic view. But Inspector Alleyn has little interest in romance; he’s investigating a murder. Cara was a deeply spiritual young woman, a novice with the House of the Sacred Flame. It seems, however, that somebody was operating from very un-spiritual motivations.