The creature below.
(DVD)

During a traumatic accident whilst on a deep-sea dive in the depths of the Atlantic Ocean, Olive, a gifted, young marine-biologist discovers an unearthly creature. Loosing her dream job, Olive smuggles the creature home, intent on studying it in her basement, unbeknownst to her devoted boyfriend Matt. Whilst struggling to re-adjust to landlocked life and recover from her recent trauma, Olive begins to realize that she and the creature share a symbiotic bond that drives her to carry out its sinister will. Plagued by gruesome nightmares, her fractured memories of what happened during the accident in the depths of the ocean begin to unravel and reveal an eldritch horror far older and malevolent than she could ever imagine, one which she has unwittingly set free. Olive's obsession leads to madness as her discovery consumes her entire humanity, with deadly results for those around her.