Sofia, a struggling Marine Archeologist perpetual thesis student, on a quest to find Atlantis as a means to redeem herself for her sister, Eevi's apparent drowning for which she blames herself, discovers the demons of her childhood are back to haunt her when she is faced with another family death. Guided by a series of unlikely thalassic companions, Sofia is forced to set off on a personal journey to conquer her fears, manifest in thalassophobia, through freediving - will she find the way to let Eevi go before she too is pulled under into the abyss?