They are, in reading order:

The Anome
The Brave Free Men
The Asutra
The land of Shant on the planet Durdane is ruled by a dictator called "The Faceless Man", or "The Anome". He is called this because his identity is literally unknown. He maintains control by virtue of the "torc", a ring of explosive clamped around the neck of every adult man or woman of Shant. Since no one knows who the Anome is, or who his agents are, fear of discovery induces most people to remain law-abiding, since the penalty for crime is detonation of the torc by remote control - without warning or trial. The deterrent effect of this method of government is unimpaired by doubt as to the actual guilt of the dead offender. An exploded head, innocent or guilty, is a vivid object lesson of the penalty for crime.

The Anome is actually not one man, but a self perpetuating and self-selected dynasty. When one Anome grows old he chooses his own successor, in a system that was instituted hundreds of years prior to the time of the story. The reason for this bizarre system of government is the extreme individuality of the folk of Shant. They are divided up into dozens of different cantons, each with it's own very individual customs and laws, but united by a common language. Prior to the ascendancy of the Faceless Man, Shant was plagued, by constant civil war and dissension. The Faceless Man not only provides the glue that holds Shant together, but operates principally by anonymous communication with the cantonal leaders. Those who lose their heads are largely those who have violated local law.

The protagonist of the story is one Gastel Etzwane, the son of a prostitute and an anonymous musician. The first two volumes of the trilogy chronicle the coming of age of Gastel Etzwane, his discovery of the identity of his musician father, his struggles to become a musician himself, the murder of his mother and sister by a race of - literally - inhuman barbarian invaders known as the Rhugoshoi, and his struggle for revenge against those same barbarians. This struggle leads to Etzwane discovering the identity of the Anome, who, strangely passive, refuses to mobilize the armies of Shant against the barbarians. Etzwane is forced to assume the role of Anome himself; and through luck and improvisation leads an eventually successful struggle against the invader. As a consequence of the social upheaval caused by the war, Etzwane lays down his office, and the torc system is abolished.

In the third and final volume, Etzwane learns - the hard way - that the barbarian invaders were the creation of an alien race known as the Asutra, who designed these caricatures of humanity in a first assay at biological warfare against the peoples of Durdane. For the Rhugoshoi are all males, they can only reproduce by sexual intercourse with human women, and they are insanely lustful. The resulting "imps" have no genetic relationship to the human mother, who is a host only. This process, by design, also renders the woman sterile, and unable to bear a human child.

The trilogy is set in the same broad Gaean Reach milieu that many of Vance's books are, and like most of his work, full of colour, culture and heroic adventure. There are wind-propelled cable-car like vehicles and explosive collars around the necks of the populace and a host of other creations that make Vance the distinctive author he is.