Cautionary tale

A cautionary tale is a tale told in folklore, to warn its hearer of danger.

Description

There are three essential parts to a cautionary tale, though they can be introduced in a large variety of ways.

First, a taboo or prohibition is stated: some act, location, or thing is said to be dangerous.
Then, the narrative itself is told: someone disregarded the warning and performed the forbidden act.
Finally, the violator comes to an unpleasant fate, which is frequently related in expansive and grisly detail.