Just got back from seeing Lights Out. It was not what you would call a “good” horror movie, but nevertheless it was Girls Underground, possibly from two different angles. I’m not going to tiptoe around spoilers here because really, this wasn’t worth it.
At first I thought the Girl Underground was Rebecca. After having moved away from home as soon as she could because of her crazy mother, she finds herself drawn back in order to rescue her little brother, who is the victim of the mother’s same old delusions…except of course they’re not delusions, she is keeping company with some kind of creature (not really a ghost per se, but a girl who was once alive and now isn’t, who was evil and abnormal even as a living person) who wants to destroy everyone in her life. Rebecca’s companion is her boyfriend, it mostly takes place in a house, she has a dead father and distant mother, so it all fits. But in the end, it’s her mother Sophie who ends up defeating the monster, and does so in order to save her own children. So if you look at it from her perspective, she might be the Girl Underground – the adversary attached itself to her at a young age, drove her even more mad, and is out to kill her loved ones. She can only defeat it by sacrificing herself.