The Firefly Squad.

May 1942. Several units of the Crimean Front troops, together with the city's residents, took shelter from the bombing in the Adzhimushkay quarries. A boy who, using neural network technologies, got into the past, faces a choice: find lost artifacts or help the defenders of the quarries. And he decides to share all the hardships of this life and, most importantly, to give hope to these people.