Possibly the best zombie film of the modern era, Train to Busan tells the seemingly-simple tale of a group of people trying to get to Busan during a zombie outbreak.
Like Snowpiercer before it, Train To Busan deals with societal issues in a tight and claustrophobic environment of a train. But unlike Snowpiercer, which was complex, metaphorical and somewhat inaccessible, Train to Busan has a pared-back plot, effective in its simplicity. It's emotional and even heart-rending at times, with the emphasis on the human aspect of the story. The moral messages and social commentary are there but subtle enough that you can just enjoy this as a film about zombies if you so choose.
Gong Yoo gives his usual stellar performance, Ma Dong-seok is excellent as well and Kim Su-an demonstrates why she's a child star to watch.
If you're tired of your zombie films being thinly-veiled xenophobia and NRA propaganda, you'll enjoy this one set in a country where no one has guns so the protagonists have to survive using their wits instead.
For action and horror - and probably quite a few tears - in a film paced as fast as the train in which it's set, watch Train to Busan.