This is billed (honest) as "a seminal film of the Australian New Wave." It was believed "lost" for many years. But they found it, and here it is. Probably the best-known actor here is Donald Pleasance, but (depending on how many old flicks you've seen), you might also recognize Chips Rafferty or Jack Thompson. It was directed by Ted Kotcheff, who went on to direct movies as diverse as First Blood and Weekend at Bernie's. But this one is less accessible and more arty.
It's kind of a horror movie, but one without monsters or any kind of supernatural goings-on. The protagonist, Grant, is a dissatisfied school teacher in the Middle of Nowhere, Australia. For Christmas vacation, he plans on going to Sydney to meet up with his girlfriend. This involves travelling by rail to Bundanyabba (known to the locals as "the Yabba"), and spending a night before catching a flight to civilization.
The Yabba is a, well, colorful place. The locals are polite, but have a knack of insisting that Grant drink up with them. And of course, Grant's money is also welcome at the local game of chance. This begins Grant's spiral into moral degradation. It's not a pretty picture, Emily.
Consumer note: this movie is probably not for squeamish folks who like marsupials. There's a drunken hunting scene that involves actual shooting of actual kangaroos, and (Wikipedia reports) involved actual drunk hunters. Reportedly, the film crew faked a power outage in order to end the carnage. But more than enough of it wound up on the DVD.