The Chinese submarine base in Mishima City is assembling a new type of submarine, which must be delivered to the navy for sea trials in two months. The intelligence agency of Country D has confirmed through advanced technical means that China's new type of submarine uses cutting-edge multi-element alloy materials, which makes the noise lower than the background noise of the ocean, greatly improving the deterrence of the submarine. The intelligence agency of Country D infiltrated through the Internet and manpower in an attempt to steal the secrets of R-4 materials in order to study the defense mechanism and take countermeasures in a timely manner. However, while they confirmed the noise reduction technology of Chinese submarines, they also exposed the lurking spy Shark No. 1 in Mishima City. The intelligence personnel of Country D, led by Brell, launched a tense and fierce confrontation with the joint military and local task force formed by our naval security department and the Mishima City National Security Bureau. In the end, these people's soldiers used their blood and lives to protect the confidentiality of the submarine, firmly fulfilled the sacred mission of national security and military security cadres, and composed a heroic hymn of loyalty to the party, the country, and the people.