Based on the Low German literary figure Till Eulenspiegel, Coster's novel recounts the allegorical adventures as those of a Flemish prankster, Thyl Ulenspiegel, directly before and during the Dutch Revolt against Spanish rule in the Netherlands.

As depicted by De Coster, Ulenspiegel carries in a locket around his neck the ashes of his father, burned at the stake outside of the walls of the city on charges of heresy – a feature never hinted at in any of the original folk tales.

As a youth, he is several times apprenticed to various craftsmen, but never remains long with any of them - especially due to his habit of taking commands literally, with hilarious and sometimes disastrous results.

Sometimes he indulges in elaborate confidence tricks, for example getting Jewish and Gentile merchants in Hamburg to pay him considerable sums for supposed magical amulets which are in fact made of animal excrement.

Eventually, he gets to Rome and obtains the required Papal pardon, through a combination of an Uilenspiegel trick played on the Pope in person and a bribe paid into the Catholic Church's coffers.

His father Claes had been arrested for his Lutheran sympathies, having been turned in by the family's odious neighbor - a fishmonger, who hoped to gain part of his victim's property under the Spanish policy of rewarding informers.

Afterwards, Uilenspiegel himself and his mother, Soetkin, are arrested and tortured horribly in each other's presence, to make them reveal the location of Claes' hoard of coins - which is now legally the Emperor's property.

Traveling on the back of a donkey, or on boats and barges with rebel-minded crews ranging the country's canals and rivers, Uilenspiegel carries secret messages and letters.

Eventually, the Dutch Republic emerges effectively free from the oppressive Spanish rule - but the Eighty Years War would drag on long past Uilenspiegel's lifetime.

No longer young, Thyl and Nele are assigned a guard tower on what has become the border with the Spanish-occupied land, from there to sound an alarm should they see enemy troops approaching.

At the book's conclusion, Thyl and Nele experience at night a magical vision, with mythical beings uttering to them a prophecy about a future time of reconciliation between North and South (i.e. what would become The Netherlands and Belgium[1]).

Nelle is able to magically eavesdrop on a very private conversation between Emperor Charles V and his son and heir Philip II; she is able to go up to Heaven and see judgement passed on the souls of Thyl's father Claes, burned by the Inquisition, and of the same Emperor Charles who on the same day died of overeating; and later Nelle gets Thyl to accompany her on voyages to magical realms where they see various fantastic beings and have allegorical visions (which actually convey De Coster's political ideas).

It is noteworthy that in the Heaven depicted in the book, the Virgin Mary has a major role - seated at the side of her son Jesus as he passes judgement on the souls of recently deceased people, and trying to temper his severity with her pity and compassion.

Embedded in the book are several chapters constituting, in effect, a Murder Mystery - a literary form not yet recognized as a distinct genre at the time of writing.

People going abroad in the night - especially young women, but also others of all ages and genders - are discovered in the morning with their necks broken, bearing the clear mark of the bite of wolf's fangs.

The German composer Walter Braunfels adapted De Coster's novel in 1910 for his second opera, the full-length Wagnerian epic Ulenspiegel, first performed at Stuttgart on 4 November 1913, revived in 2011 (Gera, Thuringia) and 2014 (EntArteOpera, Zürich - a production released on DVD in 2017 by the Capriccio record company).

Wladimir Vogel was a Russian composer who wrote a drama-oratorio Thyl Claes in the late 30s or early 40s, derived from De Coster's book.