About the book: year / The main character is on vacation, experiencing financial problems. Receives an offer to earn money by moving things on a scientific expedition. He wants to refuse, but under pressure from his wife Olga agrees. In addition to scientists, the expedition includes armed mercenaries and people like the hero. Having arrived at the place, the leader of the expedition, Theodor Emelyanovich, conducts a ritual, as a result of which one of the porters dies, and the rest find themselves in a dungeon called the Abyss. Here travelers are attacked by monsters. After being rescued, the hero meets one of the scientists - the girl Oksana. They become close. The journey continues. The creatures attack again, and everyone flees. During a halt, the mercenary commander, the Beast, sends the hero and another porter to carry out the assignment. Sensing a catch, the hero sabotages the mission and runs, and his partner is absorbed by a strange black substance. Wandering alone, the hero ends up in many strange places and finds people from the expedition. He learns that Oksana died from a dark substance called the Black Devourer. After a halt, the Devourer kills the surviving scientists. The last porter is sacrificed to open the door, and the hero understands: they were taken to be used as keys. One of the mercenaries, the woman Vobla, believes that the hero could have been used differently. People meet Casimir, Theodore’s brother, who has been in the Abyss for more than a hundred years. It turns out that the expedition was sent by the criminal authority Utyug. He is dying, and in the Abyss there is a certain Fiery Stream, bestowing immortality and absolute health. The path continues. The mercenary Krugly, Vobla’s friend, dies in a clash with stone monsters. The rest are attacked by an invulnerable creature - the Phoenix. The hero escapes with Vobla, but Phoenix does not lag behind, and the woman falls into the waterfall. Having survived the cave of giant spiders, the hero meets the survivors. A skirmish occurs where only the hero and Theodore survive. The fiery stream and the exit to the outside are not far, but the travelers are again pursued by the Phoenix, and Theodore enters the fight. The creature flies away, and the wounded Theodore is saved by his brother. The hero observes the Flow from afar and climbs out through the Endless Staircase. At home, he is visited by the people of the Iron and forced to go into the Abyss again.