184 pages; hard cover; full color

Six miles below the surface of the ocean, Mia has to solve a locked-room murder mystery before the crime scene is completely flooded. As the crew tries to save the Dept. H base from destruction, some of them start to take matters into their own hands. But the bottom of the ocean is full of unknown dangers, and with time running out, rescue is almost impossible. Collects issues #7-#12.