It's difficult to provide a complete assessment of this striking Kiwi feature without engaging in what might seem like - but is not really; the plot point occurs less than 20 minutes in - a major spoiler.
So if you want to see it - and see it you should - completely cold, let your eye skip the next three paragraphs right now. (Start at "The newest fruit ...")
For me, the major improbability that dogs an otherwise assured piece of work is the idea that a mother - any mother, anywhere, ever - would accept as her own someone else's son when (here's the important bit) she knew that the boy concerned had been abducted and that his real mother was inhabiting a panic-stricken hell.
Director and writer Currie seeks to deal with this credibility challenge by having a character tell us that the boy's real mum and dad are not fit parents and, to be sure, the world his two main characters come to create is one fraught with a perfectly plausible insanity occasioned by their own bereavement. But when the film's mother first discovers what happens, her response is one of horror: the process by which she becomes part of the plot's conspiracy is far from convincing and, for me, it remained a fatal flaw.
The newest fruit of the NZ Film Commission's excellent low-budget Escalator project, which has given us Fantail, this festival's Orphans & Kingdoms and Housebound, and Existence, which played in the 2012 festival, Everything We Loved opens on Charlie (Stewart) at home and looking after 5-year-old Tommy (Clarkson).