Four travelers emerge from the ocean, heading towards the desert. Among them is the main character Rudi, a descendant of the ancient Lyritans. Their goal is to find cities of spirits, habitats of those who lived long before them. However, everything does not go according to plan. There are delays along the way. First, Rudy is bitten by a snake, and an unexpected encounter with a saber-tooth traps them in the sand. In a battle with an unknown intelligent race, Rudy is captured, and he begins his independent journey on this planet far from his team. Already languishing in captivity, he realizes that he is a hostage. However, he does not lose hope of getting out. In the rainy city, he remains as a prisoner; from time to time, the Pericons (the race that captured him) interrogate Rudy. In a dream, the main character gains the ability to understand foreign languages, which is how he found a language with his future partner Crani (an overseer from the Perikon family). Over time, she agrees to help him and implements an escape from the rainy city into the jungle. In the jungle they make an amazing journey all the way to the mountains, hiding in a cave while they sleep. Ancient mastodons disturb their sleep, but then leave the cave. Rudy and Crany continue their journey into the stony steppes, stretching beyond the mountains, leading to the ancient city of spirits. Rudy and his companion remained unnoticed by an unidentified flying object that was flying over the territories. Next, the main characters penetrate into the city’s underground and spend the night in a shelter. The city’s underground greets them inhospitably: first, a trap of a carnivorous plant, then a labyrinth of tunnels awaits Rudy and Crany, who trustfully follows him. An attempt to find a passage leads to nothing, and on top of that, Craney is kidnapped. Rudy is left alone, trying to find his partner. Meets a new race of Oberos, who captured Crani. The shootout begins unexpectedly, it is interrupted by the awakening of spirits dozing in cryogenic capsules. These spirits turn out to be none other than people who escaped from an ancient virus that destroyed humanity. People act as the dominant race, ordering the rest of the intelligent ones to follow into the regeneration chambers for further transformation. After regeneration, Rudy and Crany also become human. A new future begins for them - not as a descendant of a dolphin (Rudy) and a descendant of a caiman (Craney), but as people.