Carobou

When research chemist Kiera Underwood receives a cryptic phone call about her twin brother, she tries to contact him to no avail. Her twin sense tingles, warning her that something is wrong. When he doesn't return her call and his supervisor at Oceanic Labs claims he didn't come into work, she heads to Cold Harbor. But when she arrives in town to find the door to her brother's house ajar, she races to the lab to question his fellow employees.

Commander Mark Bishop is deliberately low-key: "I'm in the Navy." But commanding the ballistic missile submarine USS Nevada, keeping her crew trained and alert during 90-day submerged patrols, and being prepared to launch weapons on valid presidential orders, carries a burden of command like few other jobs in the military. Mark wants someone to come home to after sea patrols. The woman he has in mind is young, with a lovely smile, and very smart. She's a civilian, yet she understands the U.S. Navy culture.