Commander Donald Castillo is the commander of the Virginia class fast attack nuclear submarine Kansas. It is the latest and best that the U.S. Navy has to offer. He is asked to test a new ground-breaking countermeasure that will revolutionize naval warfare. Its code name is Apparition and he will be working with a civilian test team headed by Dr. Susan Lambert. This is game changing technology born of the Hadron Collider and the Navy brass are hungry for it. But something goes wrong during testing and the Kansas and her crew disappear off the western coast of Scotland. The American and British navies perform an exhaustive search, but find not a trace of Kansas.
Meanwhile, Castillo and the rest of the Kansas crew can not understand where everyone has gone. They can't get a response from anyone, nor can they see anything on sonar, nor can they get a GPS fix. What's going on? They see what looks like a replica of an old Spanish galleon sailing ship. Castillo decides to surface and approach the ship and ask if they know where everyone has gone. Instead of getting answers, they are fired upon and Castillo is captured. The Kansas's executive officer gets Castillo back, but not before they discover that the Spanish crew thinks it is the year 1588. How can that be?
Castillo decides to return to base only to discover it's not there! He and Susan Lambert are beginning to suspect what has happened, but no one wants to give voice to it. It's too unthinkable! Depression sets in as the crew reluctantly faces the truth. They are stranded in the wrong century, and there is no way back. They are faced with the enormous task of making a life in a preindustrial world with few survival skills or resources. Castillo realizes that at least they can watch a watershed event of history, the defeat of the famous Spanish Armada by Sir Francis Drake and Lord Howard. They will have front row seats. But something is wrong. Events as described by the history books are not happening correctly, and the Armada is much bigger than it should be. The English are losing the fight. They are heavily outnumbered and outgunned. Castillo is in a quandary. He and his ship have the power to affect the outcome. Should they act?