Morgiana

A dark psychological study of sibling jealousy and moral corruption, where a poisoner's guilt and paranoia spiral into a web of escalating crimes.

Jealous of her vapidly "good" sister's popularity, poisonous Viktoria doses pretty Klara's tea with a slow-acting fatal substance. As the latter grows hysterically weak, the former finds success increasingly compromised by guilt, blackmail, and the pesky need to kill others lest she be exposed.