# leave no stone unturned

idiom · CEFR B1

Source: https://englishreference.com/idiom/leave-no-stone-unturned
Updated: 2026-08-10

## Meaning

To search or investigate thoroughly.

## Examples

- The police will leave no stone unturned to find the missing keys.
- The detective promised the family that he would leave no stone unturned during his investigation into the accident.
- Determined to solve the mystery, the researchers left no stone unturned, examining every historical document and piece of evidence they could find.

## Origin

From a Greek oracle story: after the battle of Plataea (479 BC), the Delphic oracle advised searching for the Persian general Mardonius' buried treasure by 'moving every stone'; quoted by Euripides. (disputed)

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.