Tunnel without light. Sharapov V.G.

From the Soviet residency in the West comes a signal of a data leak from a closed research institute, a leading development in the field of microbiology and virology. The group of KGB Major Mikhail Koltsov is instructed to identify and neutralize the "mole". The operatives are convinced that formally all instructions for the protection of state secrets at the enterprise are respected. Then how does the spy manage to transmit information? Finally, the major finds a serious clue. To make sure that this is the same channel, Koltsov puts his own life on the end...