Oculus

 Before Mike Flannagan became mostly known for a string of thoughtful horror/drama miniseries, he directed (and often wrote) a string of excellent, varied horror movies - all of them thoughtful, even his sequel to Ouija, a mediocre franchise starter if there ever was one. If I had to chose a favorite I'd have to pick Doctor Sleep, but 2013's Oculus is a very close second.

 Tim Russell (Brenton Thwaites) is released from a mental institution eleven years after killing his father (Rory Cochrane). To be fair to Tim, his father had just killed his mother (Katee Sackhoff), and was coming after him and his sister Kaylie (played as an adult by Karen Gillan) next. And to be fair to the authorities that sent him away, Tim was convinced a haunted mirror caused the murders.

 His long stint under psychiatric care has disabused Tim of that notion, and he's keen to resume his life as a free, well-adjusted person. The problem is that his sister is still very much convinced the mirror possessed their father; She's got a plan to prove it... and she wants Tim to help her.

 Kaylie's been stalking the Lesser glass (as the mirror is known) over the years, and has positioned herself to work at the high-end auction house that is holding it in storage. The old family home was held for her while she was going through the foster system. Now her brother is free, she arranges for the mirror to be sent to the old house, which is almost in the same state they left it. She's rigged the place with cameras and a clever killswitch that will destroy the mirror if she doesn't constantly reset a mechanical timer.
 She doesn't just want revenge - she wants to prove her father was a victim, not a murderer - one more in a long series of souls the mirror has ruined. She's also had more than a decade to plan everything, and the plan she's come up with is clever: The mirror manipulates people's perceptions, hence all the cameras and failsafes. It feeds on the lifeforce of plants and animals, so there are plants arranged everywhere to measure how far its influence reaches... as well as a cute Boston terrier Kaylie puts in a cage in front of the mirror for it to devour; I stewing on something for almost half your life will leave you at least a little unhinged.

 All of this naturally alarms Tim, who wants nothing more than to return to a quiet life, and has more rational explanations to explain the death of their parents - but he lets himself be drawn into his sister's designs, and as the day draws to a close the past bubbles forth, giving us glimpses into the final days of the older generation of the Russell Family (Annalise Basso and Garrett Ryan Ewald play Tim and Kaylie as pre-teens). The script (by Flannagan and Jeff Howard) deftly weaves the two storylines, slowly growing darker as the mirror awakens and exerts more and more influence in both the present and the past, each  strand's events reflecting* each other all the way to an inevitable, delightfully evil conclusion.

 It's a remarkably dark psychological horror tale that focuses on perception being distorted until the characters don't know what's real and what's not. This can be frustrating - I rewatched this partly due to being somewhat annoyed by Smile 2's foray into similar territory - but I think Oculus does it the right way by putting this element front and center, both in its plot and its themes - and it never feels like it undoes what you thought the movie was about. The (minor) supernatural mayhem is substantial, too, with plenty of creepy imagery and some nasty unpleasantness. There are a couple of jump scares, but the film tends far more towards sustained dread.

 Flannagan's direction can usually be best described as elegant, and this was already the case this early in his career. It doesn't call much attention to itself here, but it blocks the actors and action beautifully and gives the house a great sense of place. Much of the film takes place during the day or in well-lit spaces, giving the murky finale a little bit more of a punch.

 More than anything else, though, the film thrives thanks to the care and depth with which Flannagan and Howard have lavished their characters, beautifully played by the cast. Gillen in particular stands out, her no-nonsense determination not quite covering up for a decade of hurt, but honestly everyone in this is really good.

*: Sorry! In my defence, I almost used mirroring.