More sci-fi than horror. There was no Hell or demons etc
This was basically another version of the Lucy movie, about what could happen when a person can use 100% of their brain at once. The visions of hell , were not really of hell, it was Olivia:s memory of the apartment block fire, which she was always thinking about in her subconsious and had issues dealing with. The serum that bought her back enhanced her psychic abilities (100% of her brain now active etc) and so she was able to project that memory into the mind of the new girl. Thats all.
The eyes turning black and her walking around like a monster etc, didn't mean she was possessed, its just this movie:s way of showing how powerful she had become. She had hyper-evolved. The dog was also going through a similar process, but at the end of the day, it was just a dog. How far could it go evolution wise?
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