On an island off the South Carolina coast, the narrator visits his friend William Legrand, a once wealthy man who has become withdrawn after finding a strange golden beetle. Legrand, together with his servant Jupiter, seems caught up in some secret scheme. A scrap of parchment with hidden marks leads them into an expedition that tests the narrator's trust in his friend's sanity. The story is a treasure hunt built around codes and ciphers, and it did much to popularise cryptography among general readers. It is lighter in tone than much of Poe's work.