Off the coast of Mozambique, somewhere in the middle of the vast Indian Ocean, the rapidly sinking artificial islet known as "Little Happy", and its last two residents are facing the effects of global warming. There, the passionate marine biologist, Dr Emma Collins, and her team are studying the impact of climate change on Great White sharks, who come to mate in the peaceful marine conservatory, when, unexpectedly, Emma's old flame, Richard Lowell, arrives on a research vessel. Now, in high hopes of capturing three rogue, genetically enhanced bull sharks, Richard drags Dr Collins in a fierce battle of survival, as the trio of fast underwater killers have already picked up the fragrant scent of human blood in the water. In the wake of the Akhelios Complex massacre in
Deep Blue Sea 2 (2018), a new bloodbath is waiting to happen, of course, in the name of science. Will humans never learn?
—Nick Riganas