It tells the story of two young friends, Polish boy Staś Tarkowski and English girl Nel Rawlison, kidnapped by rebels during the Mahdist War in Sudan.
A 14-year-old Polish boy, Stanisław (Staś) Tarkowski, and 8-year-old English girl, Nel Rawlison, live with their fathers and grow up in the town of Port Said.
Staś and Nel are captured as hostages by a group of Arabs who hope that they can exchange the children for Fatima, Mahdi's distant relative, who had been arrested by the British.
When the group arrive in Khartoum, the Arabs are disappointed by the fact that Mahdi, busy with leading the revolt, ignored their mission and turned down their offers.
Staś and Nel, exhausted by heat, thirst, hunger and poor treatment, live for some time in the city ruined by war, poverty and diseases.
They set out on an arduous journey through the African desert and jungle in the hope that sooner or later they would encounter European explorers or the British Army.
Due to assistance from Kali's tribe and the guns carried by Staś and Nel, the war is won in the protagonist's favour.
Because of his good nature, Staś and Nel command that the tribes-people of the Sambur tribe not be killed but rather united with the Wa-Hima.
Staś, Nel, Saba, King, Kali and 100 Sambur and Wa-Hima tribes-people move on to the east, which has not been mapped, in hope of reaching the Indian Ocean and being found by English explorers who might be searching for them.
After the group has gone for at least three days without any water in the scorching dry desert, the children are saved at the last moment by two familiar officers who had recovered kites inscribed by Staś and Nel earlier in their plight describing their whereabouts and destination.
[4] Wojciech Zembaty writes that the book "uses classic patterns of the adventure novel genre" and observes that "thanks to willpower, endurance and creativity [...] the travellers and castaways of these novels manage to survive in a hostile environment" citing Daniel Dafoe's Robinson Crusoe (1719) and Jules Verne's The Mysterious Island (1874) as examples.
Furthermore, Stomma criticized how Sienkiewicz depicted the Mahdi in a uniformly negative light and ignored misdeeds committed by British forces in their war against him.
He counters the argument about the novel's allegedly racist depiction of African characters by showing the example of the young prince Kali, liberated from slavery, who is "brave, creative and honourable".
[8] In 2017, Afro-Polish activist James Omolo wrote that In Desert and Wilderness "helped perpetuate existing racist stereotypes".
[11] However, just like other works by writers from this period including Joseph Conrad, Rudyard Kipling or H. Rider Haggard, who met with similar criticisms, the book can also be seen as a product of the era in which Sienkiewicz lived and his views on Africa could be seen as a sort of historical testimony, a monument from the times, when Europe was narcissistic and superior, compared to the rest of the world, in terms of material and scientific progress.