Cugel is easily persuaded by the merchant Fianosther to attempt the burglary of the manse of Iucounu the Laughing Magician, which is filled with precious magical items.

Caught by Iucounu's trap, Cugel agrees that in exchange for his freedom he will undertake the recovery of a small hemisphere of violet glass, a magic "Eye of the Overworld", to match one already in the wizard's possession.

A small sentient alien entity of barbs and hooks, named Firx, is attached to Cugel's liver to encourage his "unremitting loyalty, zeal and singleness of purpose".

There, Cugel finds two bizarre villages, one occupied by wearers of the magic violet lenses, the other by peasants who work on behalf of the lens-wearers, in hopes of being promoted to their ranks.

Cugel also falls victim to the trickery of others, such as when he is fooled into being locked in a watchtower in a lakeside town or when he is lured into imprisonment in a cave by the devious Rat People.

Cugel is a classic Vance anti-hero; though he fancies himself an aesthete and a superior being to those around him, in his actions he is a liar, a cheat, an inveterate thief, a charlatan, selfish, greedy, vicious, and so on.

For example, he bribes a priest, with all of his very valuable magical items, into tricking fifty pilgrims into a futile pilgrimage, to guard his crossing of a perilous desert – only fifteen survive.

[1] In The Eyes of the Overworld, the episode involving the Busiacos narrated at the beginning of chapter 3, "The Mountains of Magnatz", differs substantially from the novelette published in the February 1966 issue of The Magazine of Fantasy and Science Fiction.

In the magazine serialisation of the novel, at the end of "The Overworld" the character Derwe Coreme rides off in her walking-boat never to be heard of again, and at the beginning of "The Mountains of Magnatz" Cugel finds himself alone in the northern wasteland.

Cugel pays the Busiacos a jewelled button to ferry him across a river that he could just as easily have waded through and then proceeds south, refusing to believe he has been duped even when he sees a nearby bridge.

The Italian translation, Cugel l'astuto, appeared in an omnibus version together with La terra morente (The Dying Earth) in 1994, published by Editrice Nord.