Shell and Shatter. Undertow Sins, #43

"We build our shelters from the same material as our scars."Dr. Soleil Beaumont is a VA psychologist who strictly plays by the rules. Ryker Graves is a former Marine Recon operator who trusts concrete more than people. Living off the grid in a heavily fortified underground bunker on the feral Oregon coast, Ryker is a man buried alive by his own survivor's guilt. Soleil is simply there to evaluate him-until the ground tears open.
When a catastrophic 9.1 magnitude earthquake and a massive tsunami decimate the coastline, Soleil is forced to make a split-second choice: flee into the apocalyptic rubble, or let Ryker seal the blast door. Trapped twelve feet underground, they are completely cut off from a ruined world. The bunker is built to withstand the ocean's fury, but it wasn't designed to contain two people fighting their deepest demons.
As the generator fails, plunging them into absolute darkness, the oxygen clock starts ticking down to zero. In the sweltering, suffocating blackness, the professional distance between doctor and subject evaporates. Forced into intense, desperate proximity, Ryker and Soleil discover an undeniable, consuming spark. With time running out, they'll learn that the most dangerous thing isn't the disaster raging above-it's letting someone past your ultimate defenses.