Ten canoes, three wives, one hundred and fifty spears...trouble

A story within a story within a story. In Australia's Northern Territory, an Aboriginal narrator tells a story about his ancestors on a goose hunt. A youngster on the hunt is being tempted to adultery with his elder brother's wife, so an elder tells him a story from the mythical past about how evil can slip in and cause havoc unless prevented by virtue according to customary tribal law.