The Euthyphro is a Platonic dialogue, reputedly between Socrates and a "theologian" named Euthyphro. The dialog takes place shortly before Socrates' trial, which forms the dramatic backdrop to the story. Since Socrates has been accused of impiety, he seeks advice (in, of course, ironic fashion) from Euthyphro, who also has a court case ahead of him.
As with all of the dialogues of Socrates, the question of how much of it is an accurate reflection of what Socrates said or believed, and how much of it is Plato trying to construct a system, is something that would take a great deal of expertise to resolve. I can not give definitive views on ancient Greek linguistics or social practices.
The Euthyphro is most famous for introducing the "Euthyrphro dilemma": do we consider things good because the gods (Or God) like them, or do the gods/God like thing because they are good? It is an important question to ask, and to a modern reader, it might determine whether we view God (or divinity) as a principle or an agent. It is also, almost 2500 years later, something that's paradoxical nature seems less than crisp: another version of asking whether God can make a stone so heavy he can't lift it.
But what is more interesting to me about this dialogue is the background, and the reason that Euthyphro, like Socrates, is involved in a court case, although as a plaintiff, instead of as a defendant. Euthyphro has charged his own father with murder, or manslaughter. The case is explained in one paragraph, but basically two of Euthyphro's household servants (or possibly slaves) got into a fight, and one of them died. The murderer, was, in turn, shackled and "thrown into a ditch" by Euthyphro's father, where he died of exposure. Euthyphro has charged his own father with murder (or perhaps manslaughter), even though, according to the text, suits were usually only brought by the relatives of the dead. Socrates is astonished that Euthyphro would put the abstract idea of justice ahead of family obligation. He then goes on to ask Euthyphro whether he knows if this is truly the pious thing to do, something that Euthyphro can not provide a systematic answer to.
So the point that often gets lost behind the logical paradox is that Socrates is not using reason, rationality or questioning to "subvert" hierarchy or convention, or to make a case for universal justice. For that matter, Socrates doesn't even seem to show a normal amount of empathy for the two people who died. Euthyphro's notions of innate human value, and that justice is based upon us, probably fits our modern conception well, and the fact that Socrates can find a semantic paradox in it doesn't mean (at least to me) that Euthyphro's viewpoint is naive.
In modern times, at least since The Enlightenment, we usually think of rationality as being emancipatory in nature. The point of thinking and asking questions is to dismiss our prejudices and be able to understand others better. And it is easy to project these ideas backwards, and think of Socrates and Plato as basically being interested in liberation or emancipation by questioning the ideology of hierarchies and traditions. But when reading the actual texts, we find the message is often quite different.