Almost everyone's heard of characters you love to hate.
Problem is, not all of us love it.
The character of Matt, the older brother, made it REALLY difficult for me to enjoy most of this movie. He's such an unmitigated pile of rancid human garbage.... Every time I saw his face or heard his voice, I just thought, "Would you please just eff off and die already?" (That said, it would be a terrible sin against Fionn Whitehead to omit mention of what an excellent job he does playing this character. He's 97% as believable as he is despicable. I think the other 3% can be explained if we assume Fionn is just a generally nice guy who deep down doesn't understand people like Matt. Unfortunately they do exist. Anyway, here's hoping Fionn does more work like his brilliant performance in the Black Mirror special Bandersnatch.)
Thankfully the younger brother Joey is really the main character, so we spend more time with him than with the trashstorm that is his brother. Joey really is a good kid without any adequate role models, struggling to figure out how one goes about being a good person in a world that's mean as hell. If there's any compelling reason to watch this movie, it's the character of Joey.
The plot is relatively thin (which should be obvious; it's a movie about a boy talking to a guy down a hole) but what is there mostly works. It's only toward the end that it starts to push the limits of credibility.
Bottom line, a fair character study of a good boy in a bad world, and an effective psychodrama. Just don't expect satisfaction, and don't be surprised if Matt brings your blood to a rolling boil.
