This movie is pretty slow, but I think it has something to do with a woman who had a bad childhood so she ends up creating a perfect family where they don't hold any secrets...except of course they do. The dad is skipping work and cheating on his wife nonstop and jacking off in the bathroom to porn magazines, the daughter is skipping school and exploring her sexuality and the son has pretty much shut himself away in his room where he's creating his own private fantasy world on his computer.
I love the idea for the movie and the style is very interesting, but it just beat around the bush way too much and tried too hard to be mysterious without ever giving the viewer a payoff. I can't recommend it. If it had went ahead and pushed the envelope a little like Miike's VISITOR Q or Sono's NORIKO'S DINNER TABLE then things would be different, but as it is HANGING GARDEN never goes anywhere interesting or engaging. Please don't think it's a bad movie, just average and not worth wasting two hours on.