The deadly tides of change rise above the surface in the exciting third chapter of the best-selling action/adventure series, Fathom! Humankind faces a new threat to their existence from the ancient and powerful underwater race - the Black - while the return of the villainous Killian sends shockwaves throughout the already-devastated world of the Blue. Meanwhile, Aspen Matthews attempts to adjust to life above the water, but a future - and past - threat emerges to disrupt her safe haven!
— Description from Comic Vine community (comicvine.gamespot.com).
