Some of these pictures and descriptions may give away plot details that you might not want to know before watching the film.
This is a strange and almost incomprehensible but fascinating and very well made pre-apocalyptic mystery that involves a white tax attorney in Sydney, Australia, who defends five Aborigines accused of a ritual murder. He begins to have various premonitions and hallucinations and vivid dreams - the sort of mystical stuff we see in a lot Australian movies with Aboriginal peoples in them.
It begins with some crazy weather happenings including hail falling in the desert, black rain made of petroleum, and torrential rain in the city. We see lots of frogs on the ground after one of the rain storms. Obviously, frogs come out of hiding when it rains, but it might be that we're supposed to believe that the frogs fell from the sky with the rain, because at the end of the movie we see a cave painting made by an ancient South American civilization that appears to show frogs falling from the sky.