在这部玛利亚·韦恩系列第一季: 黑蝴蝶犯罪片中,办公室一场火灾后，人们发现了一具已经烧成炭的女式。很快人们就发现她是死于非命，她被塑料袋罩住并被浇上汽油，就这样被火焰活活烧死。
继而又有两起同样作案手段的命案发生，哥特兰警方确信这是一宗连环杀人案。但是关于被害者之间的关联，谁会是下一个被害者，警方毫无头绪。玛利亚·韦恩负责这起命案，她对于凶手的作案动机与被害人的关系也是一头雾水。与此同时，她的同事阿维迪森的忠诚也面临严峻的考验。
Swedish with English subtitles. The charred body of a suffocated medium lies in the gutted remains of her office after a fire. When two other murders take place in the same manner, Maria Wern is forced to lead an investigation in which the motive and the connection between victims remains unclear. At the same time, her colleague Arvidsson's loyalty is forcibly put to the test.
