Jerusha Bailey works in the U.S. intelligence service for 50 weeks of the year. The other two weeks she is a Naval Reservist.
While on her two weeks drill in England, German U-Boats attempt to gain control of the North Sea while trying desperately to keep U.S. assets from being involved in hopes of delaying American intervention in their plans.
When the Captain of the USS Ramage is killed in an explosion that sweeps him overboard, the next senior line officer aboard is Ms. Bailey (known as CDR Bailey for her two weeks of drill).
She is qualified for command and is given temporary command. This ship's Executive Officer, (also injured) has to be medi-vac'd off the ship for treatment.
The Ops Officer is not trusting of the reservist's abilities and tries to fight every step of the way while Ramage tries desperately to track a submarine that is so silent underwater the first any knows of its presence is when their ship is struck by a torpedo.
Follow CDR Bailey as she tries to sort out the "friendlies" from the enemies all the while trying to keep her crew and ship safe.