The story begins with Liang Chen, an expert in marine acoustics. While sorting out the belongings of his late wife, scientist Lin Wei, he accidentally cracked an encrypted file called "Sigh of the Sea." The document revealed a shocking secret: at a depth of 10,000 meters in the Mariana Trench, there is a mysterious sound wave that cannot be explained by science and seems to be filled with wisdom and emotion - the "Sigh of the Sea". And a business giant named "Abyss Horizon" is trying to erase it forever.
In order to fulfill his wife's last wish and reveal the truth, Liang Chen and his young colleagues took risks and privately drove the deep submersible "Rover" into the abyss. In the deepest part of the earth, they witnessed a miracle that subverted human understanding: the source of the "Sigh of the Sea" was not a certain creature, but a huge crystal-like life that symbiotically existed with the earth's crust and covered the seabed - the living planetary consciousness "Gaia".
