The novel takes place in Central Europe of the 16th century (mainly in Flanders), split by religious conflict and shaken by wars. The main character is Zeno Liger, an alchemist, doctor and naturalist. The original title of the novel is the Black Stage (or Blackening Stage) - the name of the first and most complex stage of the alchemical process - the Great Work. The essence of the Black stage is the “division and decomposition of substance” to the state of a certain amorphous “black mass” of primary elements, in which, as in the primordial chaos, all potentialities are hidden. According to the author, the Black stage also symbolically denotes the attempts of the spirit to break out of the captivity of habitual ideas, routine and prejudice. Zeno goes through his “black stage” against the backdrop of the horrors of Europe during the era of religious wars. Most of the characters in the novel die a painful death; there are frequent descriptions of the atrocities of that time. A kind of inserted novella in the novel vividly and harshly depicts the activities of the “King of Munster” John of Leiden and his minions, the tragedy of Munster, which fell victim to the madness of fanatics, and the bloody finale of the Anabaptist sect.