The death of an unassuming cashier turns out to be due to cyanide poisoning, and investigations into the case lead to the discovery that it was a murder.
The explosion of a 4300 tones Kauper furnace brings up an inquiry, conducted by Stefan, a Romanian Communist Party activist. He is trying to reveal the truth.
Refusing to give protection to an accomplice to a crime who had provided him with useful information, Major Tache puts his life in danger by being threatened by an old gangster who signs his messages "Death".