Dominique slows the black Pronto Spyder convertible, keeping the roadster just under fifty as she passes through the Sanibel Island bridge toll booth. Electronic sensors record her vehicle’s license plate and VIN, the information instantly fed to the Department of Transportation, which adds the amount of the toll to her monthly transit bill. She keeps the car under fifty for the next mile, knowing she is still in range of the automated system’s radar gun.

Dominique maneuvers the Spyder across the bay bridge to Sanibel and Captiva Island, a residential and resort area nestled on a small island on the Gulf Coast of Florida. She drives north along the heavily shaded single-lane roadway, then winds her way west, passing several large hotels before entering a residential area.

Edith and Isadore Axler live in a two-story cube-shaped beach home situated on a half acre corner lot facing the Gulf of Mexico. At first glance, the exterior redwood slats enclosing the home give it the look of an enormous party lantern, especially at night. This protective layer of scrim protects the structure from hurricanes, creating, in effect, a house within a house.

The south wing of the Axler home has been renovated to accommodate a sophisticated acoustics lab, one of only three on the Gulf Coast interfaced with SOSUS, the United States Navy’s Underwater Sound Surveillance System. The sixteen-billion-dollar network of undersea microphones, built by the federal government during the Cold War to spy on enemy submarines, is a global grid tied to Navy shore stations by some thirty thousand miles of undersea cables.

As the military’s need for SOSUS began to dwindle in the early 1990s, scientists, universities, and private businesses successfully petitioned the Navy for access to the acoustics network. For oceanographers, SOSUS became the Hubble Telescope of undersea exploration. Scientists could now hear the super-low-frequency vibrations made by ice floes cracking, seabeds quaking, and underwater volcanoes erupting, sounds normally lying far below the range of human hearing.

For marine biologists like Isadore Axler, SOSUS provided a new way of studying the planet’s most intelligent ocean-dwelling life-forms: the cetaceans. With the assistance of the National Fish and Wildlife Foundation, the Axler home had become a SOSUS acoustics station, focusing specifically on the cetacean inhabitants of the Gulf of Mexico. Using SOSUS, the Axlers could now record and analyze voiceprints of whales, identify species, count populations, even track single subjects across the northern hemisphere.

Dominique turns left down the cul-de-sac, then right into the last driveway, comforted by the familiar sound of pebbles crunching beneath the weight of her roadster.

Edith Axler greets her as the convertible top snaps shut into place. Edie is an astute, gray-haired woman in her early seventies, with brown eyes that exude a teacher’s wisdom and a warm smile that projects a mother’s love.

“Hi, doll. How was your drive?”

“Fine.” Dominique hugs her adoptive mother, squeezing her tight.