Euthyphro is a dialogue in which Socrates discusses the nature of piety with the title character, who prosecuted his own father in order to avoid the ritual pollution associated with a murder. Socrates uses his characteristic mode of questioning (the elenchus) to demonstrate that Euthyphro does not know what piety is. There is a significant edge to the dialogue's satire, given its dramatic setting as Socrates is on his way to answer charges against him, which would ultimately result in his conviction for impiety.
Euthyphro has often been the first Platonic dialogue read by ancient and modern readers alike, as part of a sequence that continues with the Apology, the Crito and the Phaedo. This has the advantage of providing the reader with Plato's account of the events surrounding the death of Socrates in dramatic order, while also giving some idea of the range of styles employed in different dialogues.
While the religious issues involved in Euthyphro's case may be perplexing to the modern reader, it is a good example of an 'early dialogue' in which Socrates' questioning exposes the inability of his interlocutor to define the particular virtue which he professes. The key question, with profound implications for later religious thought, has become known as 'Euthyphro's Dilemma', roughly 'is something pious because the gods command it, or do the gods command it because it is pious?'
Free Online and Downloadable Texts
Gutenberg: Euthyphro by Plato, translated by Benjamin Jowett, multiple formats.
Internet Classics Archive: Euthyphro. English online text with downloadable .txt file (Jowett).
Social Science Research Network: Euthyphro. English pdf (Woods & Pack 2016).
University of Adelaide (Internet Archive): Euthyphro, translated by Benjamin Jowett. EPUB, HTML and MOBI formats.
History of Philosophy without any gaps: Method Man - Plato's Socrates, podcast by Peter Adamson.
History of Philosophy without any gaps: Raphael Woolf on Socrates, interview podcast by Peter Adamson.
History of Philosophy without any gaps: In Dialogue - The Life and Works of Plato, podcast by Peter Adamson.
Librivox:Euthyphro- public domain audiobook.
Approaching Plato: A Guide to the Early and Middle Dialogues
Dale E. Burrington: Guides to the Socratic Dialogues.
Internet Encyclopedia of Philosophy: Divine Command Theory.
PhilPapers: Plato - Euthyphro - open source papers
Stanford Encyclopedia of Philosophy: Plato's Shorter Ethical Works.
The Great Conversation: Further reading at Tom's Learning Notes
Ancient Greek resources: Learn to read Greek classics in the original.
Bloom's Western Canon: The Dialogues are listed.