Young scientist Jamal Zakhidov is convinced that the ruins of the ancient city of Aran are located in Azerbaijan. Zakhidov is seeking to organize an expedition to the area where he believes Aran is located. Zahidov's friend, a young archaeologist named Jalil, is also well versed in geology. He believes that the rocks he accidentally found at the foot of Gyzyl-Gaya contain valuable materials. But Imam-zade, a secret agent of a foreign intelligence service, steals these samples. The expedition members meet an old man named Murtaz. The old man recognizes Imam-zade as the son of Suleiman-bek, the former ruler of these lands, who killed geologist Karimov, who was conducting research here in 1920. Realizing that he has been exposed, Imam-zade blows up the cave in an attempt to destroy the expedition. But the locals rescue the expedition members. Imam-zade is detained by MGB officers. Uranium is found in the rocks discovered by Jalil at the excavation site...