In the cold waters off the coast of northwestern Washington, the Cold War rages on. The USS Ohio, a newly refitted Trident ballistic missile submarine based in Bangor, Washington, is a source of great curiosity to the Russian military. If their intelligence is to be believed, the US Navy now possesses the technical ability to render its fleet invisible.
When a scuba diver is killed in the waters that US Coast Guard Commander Matthew Reynolds patrols, Reynolds finds himself caught up in a war of international intrigue. Tanya Andrushyn, a specialist from the US Navy's satellite intelligence operation in Hawaii, is called in to investigate. Just how did the Russians manage to plant deep-water spy buoys in the waters of the Strait of Juan de Fuca without being spotted?
A group of specialists and their secret team of trained dolphins are also brought in to neutralize the sono-bouys. When one of the dolphins gets trapped on the ocean floor, however, Andrushyn and her team must make an impossible choice: sacrifice the animal and risk detection or risk her own life to rescue it. To even attempt such an operation, they risk disclosing the existence of top-secret underwater breathing-unit technology. She makes her decision ... and soon finds herself in need of rescue.
Andrushyn suspects the sono-buoys are uploading data via satellites, so she and Reynolds try to trick the equipment into sending misinformation instead. The race is on to complete the modifications before their plan is discovered.