Marie Enger

The remaining survivors of Dept. H abandon the deep-sea base and prepare for their long-awaited ascent. But life above the waterline remains uncertain for the team, and the pressure to solve Hari's murder continues to strengthen its grip on Mia. Secrets and memories begin to surface, but before Mia can unpack the mystery, she must decide the fate of those still stuck six miles below sea level. As the water rises, Mia's time runs out.

Six miles below the surface of the ocean, Mia has to solve a locked-room murder mystery before the crime scene is completely flooded.