They're Here (13:16)
Head on the Door Productions; IMDb; Sid Zanforlin; YouTube

Sam is a 12-year-old girl who is into sci-fi, and enjoys playing pretend with her grandmother. That is, until her gran has a stroke that leaves her catatonic. Sam believes her gran has been possessed by an alien, and tries to get it out by various methods of potentially killing her gran. This naturally horrifies her father (presumably a widower), who sends her away to stay with her aunt. But Sam comes back to keep trying to "save" her grandmother. I won't say how it ends, but I will say one of the scariest things about this short film is being unsure, as you watch it, whether Sam is right or not. It is fiction, after all, so maybe she could be right, although in real life she (almost) certainly wouldn't be, and her attempts to save her gran would be deeply disturbing and ultimately homicidal. The film kept me wondering until near the end how the story would turn out. And I'm happy with how it ended. I can also say that I liked all the acting from the three main characters. And the beginning of the film did a good job of establishing the loving relationship between Sam and her grandmother, as well as setting up Sam's seemingly crazy belief about what happened to her. I found it to be some really tight storytelling.