A long time ago, the Robber Nightingale managed to defeat Ilya Muromets by cunning. He rewrote history, appropriating all the exploits and glory of the hero. Thanks to the elixir of immortality, the Nightingale has survived to the present day. And now he wants to revive the dark god Veles, to whom he sold his soul at that time. Today, only the family of our heroes knows this secret. The father of the heroes, Professor Kiselyov, manages to find Muromets in the north, in the ice of an underwater cave, where the last battle between the hero and the robber took place. Thanks to Kiselyov's development — the steel heart — Muromets returns to our world. However, this feat costs the professor his life. Now his sons, Maxim and Egor, will not only have to stop the Nightingale, but also return the honest name of Ilya Muromets — in the fights of giant robot warriors on the Roboaren.