Which modern phrase means to begin a series of unexpected troubles, like Pandora opening her container?

The modern phrase “open Pandora’s box” means to begin a series of unexpected troubles.

The idiom comes from the Greek myth in which Pandora opens a sealed container and allows destructive forces to escape into the world. In everyday English, it is used figuratively when an action or investigation creates many difficult consequences that cannot easily be reversed.

The phrase usually appears as “open a Pandora’s box” or “open Pandora’s box.” It can describe political decisions, technological developments, family disputes, legal cases, or any situation where one discovery exposes a larger set of problems. The expression is not normally limited to literal curiosity.

The idiom’s wording reflects the later “box” version of the story. Hesiod’s original Greek account refers to a pithos, a large storage jar, but European translations and retellings made the box the standard image. The phrase is consequently based on the cultural form of the myth that became most familiar in English.