What is Zhang Jiabei’s upcoming horror flick “Midnight Heart” all about? It’s hard to say, really. The first trailer for this intriguing Hong Kong shocker is completely silent, which makes deciphering its content more than a little difficult. The second clip makes things a little clearer, but not by much. All you really need to know is that a) the story looks incredibly twisted, b) the film features Simon Yam in a prominent role, and c) Hong Kong horror movies are almost always entertaining. They might not be the best pictures on the planet, mind you, but at least they’re watchable. Most of the time, anyway.