Goodnight Mommy Severin Fiala and Veronika Franz

Goodnight Mommy Severin Fiala and Veronika Franz
Goodnight Mommy is difficult to discuss without spoiling.
The eerie and disturbing debut film by Veronika Franz, a long-time collaborator with the sensationalist social-satirist director, Ulrich Seidl, and Severin Fiala is definitely a horror — perhaps the ultimate horror for a mother — but it doesn't initially present as such, being more of a slow-building psychological thriller about identity. Although, even stating that it's about "identity" is a bit glib, since it's about several psychological and existential divides between parent and child, exploring how children interpret and rationalize challenging situations.
When things start, an unnamed mother (Susanne Wuest) is returning home to her twin sons, Lukas (Lukas Schwarz) and Elias (Elias Schwarz), covered in facial bandages. At first, things are relatively normal, with the mother playing games with her sons, apologizing for her physical limitations and need for rest, but there's a natural sense of discomfort that stems from her bandages and the overall lack of facial reactions or humanizing characteristics. 
This disconnect is exacerbated by the mother's tendency to loom in the periphery. We spend most of our time with Elias and Lukas, watching them explore the woods near their home, who eventually bring a sick cat into their bedroom and hide it from their increasingly temperamental mother. Since she's often sleeping, only emerging to lash out at the boys for having a generally snarky disposition, there's a sense of coldness in the home. This is why it's not surprising that the twins come up with justifications for their mother's behaviour, speculating about the possibility that this bandaged woman might be a complete stranger.
What Fiala and Franz explore here is the eventual psychological effects of isolation. Occasionally, there are horrific inserts of the mother either emerging as an unrecognizable demon from her bandages or being filled with cockroaches, which ultimately visualize the sort of horrors that the boys are projecting onto her blank canvas. Since there's no meaningful connection or dialogue between the boys and her mother during her recovery, their fantasies and paranoia are allowed to fester and expand into a sort of delusional psychosis. The terror here is that of broken bonds and the extent to which dramatic changes in human behaviour feed paranoia and anxiety: What does it mean if our only support system suddenly turns on us or disappears, particularly if our minds are still trying to make sense of the existential void?
There are an abundance of fascinating concepts and notions that arise from Goodnight Mommy. It's a psychologically rich work that has the sort of measured pace and eye for detail that allows the audience to analyze and assess what they're witnessing. Though things eventually escalate into a rather extreme situation, it's not milked for cheap scares or brought about illogically; we're given enough time with these boys to understand their motivations, and provided with enough disturbing imagery and discomforting silence that the climax makes sense.
In a way, one of the main twists, while certainly shocking and revelatory, impedes on some of the established integrity, seeming like a bit of a gimmick (like the sort of self-conscious spectacle that would be in a lesser movie). But, because of the attention to character motivations and the manner in which the action unfolds, it ultimately works for the story and enriches what's already a very comprehensive thematic tapestry. Goodnight Mommy is a very assured and polished feature narrative debut that definitely holds repeat viewing value.