Jess (Ella-Rae Smith) has a fairly straightforward life in a beach resort town, still troubled by the death of her mother ten years before. However, when she meets gorgeous tourist Ben, things become much more problematic (Matthew Daddario). After a night of intense romance, Jess wakes up on Ben's boat to find that he has taken them out to sea. She is reluctant at first, but quickly accepts the domesticity Ben seems to be offering. When Lexie (Jessica Alexander) shows up unexpectedly, it sets off a perilous game of cat and mouse in which she and Ben accuse one another of telling terrible lies. As a result, Jess is forced to choose a side and fight for her life.
However, if there is one area where Into the Deep excels, it is in encouraging true mystery. Cox has trouble building tension, but when Lexie's genuine intentions are revealed, there is a spark of excitement. Ben is lying, or is she? There is no simple solution when the audience is squarely in Jess' position, and this is what makes the story as it develops captivating. Unfortunately, it should be emphasised that this occurs very late in the relatively little running length of Into the Deep. The lack of suspense is partly caused by how quickly the main idea is established; it takes some time to fully go into what is happening between Lexie and Ben.
Into the Deep is a weak thriller. It works reasonably well as a mystery, but it takes too long to reach the resolution. Those hoping for mind-blowing plot twists may be let down. Although Into the Deep excels in several areas, it ultimately lacks the weight to fully embrace any of its intriguing concepts. By the time the three protagonists' struggle comes to a violent conclusion, one just wishes that it had been a little more interesting.