Set aboard the submarine Leviathan D. S. V. (Deep Submergence Vehicle), this novel focuses on the early years of the International Multiple Threat Alert Command and its defense arm, the United Earth Defense Command. In the early 21st century, the United States was attacked by forces from Al-Qaeda. The United Earth Defense Command commissions the construction of the submarine Leviathan D. S. V. to keep the peace and explore the vast oceans on Earth.