My explanation on this movie central theme (Spoiler)

This movie makes much sense if we understand it at a very symbolical level. We have to see the characters as victims of abuse because the movie tells the viewer how physical/sexual abuse can screw a person's perception of realty forever and make her descend into insanity and then death..

The two children in the movie are seen as ghosts since the abuse of their parents/ in this case fathers is the worst thing it could happen to them. It kills their innocence and no one knows what happens because people are oblivious to those thingseven when there are enough cues to point to them.

For example Hilge, Anna's friend..though she tells him repeatedly that she heard and saw something dubious in her block he reassures her she's ''just imagining'' and not take her seriously...WHY not call the police or do something? A child's life would have been saved earlier if both of them Anna and Hilge would have woken up to the baby's call. You see what i hint at? The life of another abused boy just like Anders' was ( at the end we found out he was dead for two years Anna's husband being a psychopath)could have been saved !!The same occurence that Anna lived 2 years ago happpens again and this time The Mother of that boy, just like Anna doesn't intervene and nobody else does it until it's too late..

Now returning to Anna, at the beginning of the movie we see her in a perpetual fear and trying desperately to protect her son though she doesn't deal with her mental sanity and post traumatic shock. At the dinner table she has a brief conversation with Hilge where she says she doesn't remember anything about her childhood or past just one short memory of being with a woman / her mother maybe and being at ease..whie Hilge remembers everything in detail but doesn't act on those memories to change the course of the story untill the ghost of the dead boy appears to put him in guard, to say to him ''Remeber how you were one just like me..an innocent little boy, in pain''..

So because they were both victims of abuse earlier in their lives they are somewhat dysfunctional and not present to notice what happens next to them because they're both troubled by loss of a family member who played a major role in the actualising of their victimhood and sense of abandon.

So the murder of the red jacket boy goes uncheked until the UNderworld plane sets in. The dead innocent victims call for justice and awaerness from the adults and the only adult who can do them justice is Hilge who suffered abuse just like both of the boys but he somehow managed to survive and cope with it.
His mother unlike Anna might have saved him at the right moment,Anna failed to protect her son so her life is ruined by guilt to the point of driving her over the edge.Hilge's life is also ruined by losing his mother and then Anna who reminds him of her but he lives on doing justice to the missing dead boy..
It weird though that while at work Hilge doesn't recognize the dead boy's father who complains of the same issues as Anna so corruption and evilness go uncheked further without no one to care for it.

We get a serios hint on this issue when the social services guy makes advances on Anna and tries to take away her son, aggravating the situation. It's a very well done film as far as this issue is concerned but as far as i see people who saw this movie don't quite see the wood for the trees, trying to deliberate if it was a horror or a thriller with a very surrealist vibe..I think it was mostly a brilliant psychological drama on a very delicate isssue..