chinguga julgeorireul miri malhae beoryeoseo ajik an ilgeun dokjadeureun hwanal geos gata.

-가 marks 친구 as the subject of the clause 친구가 줄거리를 미리 말해 버려서.

Here, 친구가 sounds like it was my/a friend who did it or simply introduces the subject neutrally. If you changed it to 친구는, it would feel more contrastive or topical, like as for my friend....

So in this sentence, 친구가 is the most natural way to say that the friend is the one who spoiled the plot.

줄거리 means the plot or the storyline of a book, movie, drama, etc.

It takes -를 because it is the direct object of 말해 버리다:

• 줄거리를 말하다 = to tell the plot
• 줄거리를 미리 말해 버리다 = to go ahead and tell the plot in advance / spoil it

So 줄거리를 is the thing the friend told.

미리 means in advance, ahead of time, or beforehand.

In this sentence, it shows that the friend told the plot before the readers had read the book. That is why it feels like a spoiler.

Compare:

• 말했어 = told
• 미리 말했어 = told beforehand

So 미리 is important because it creates the spoiler situation.

The pattern -아/어 버리다 often adds a nuance such as:

• doing something completely
• doing something regrettably
• doing something that cannot be undone
• doing something unintentionally or in a way the speaker dislikes

So 말해 버리다 is not just to tell. It suggests something more like:

• to blurt it out
• to go and tell it
• to spoil it

In this sentence, 친구가 줄거리를 미리 말해 버려서 has a clear negative/regretful nuance: the friend revealed the plot, and that was a bad thing.

말해서 would simply mean because [someone] said/told it.

말해 버려서 adds the feeling that the action was unfortunate or annoying. It makes the sentence sound more like because my friend went and spoiled the plot rather than the more neutral because my friend told the plot.

So 버리다 is what gives the sentence its emotional coloring.

Here -아서/-어서 connects two clauses and gives a reason/cause:

• 친구가 줄거리를 미리 말해 버려서 = because my friend spoiled the plot beforehand
• 아직 안 읽은 독자들은 화날 것 같아 = readers who haven’t read it yet will probably get angry

So the whole sentence means that the second part happens because of the first part.

In everyday speech, -아서/-어서 is a very common way to say because.

읽은 is the past/adnominal form of 읽다, and in this context 안 읽은 독자들 means readers who have not read it.

This structure is very common in Korean:

• 안 + verb + -은/ㄴ noun
• 안 읽은 책 = a book that has not been read
• 안 읽은 독자들 = readers who have not read it

By contrast, 안 읽는 독자들 would mean something more like readers who do not read or readers who aren’t reading, which is not the intended meaning here.

So 안 읽은 is the natural way to say haven’t read yet before a noun.

아직 means still or yet.

Together, 아직 안 읽은 means have not read yet. This is a very common combination:

• 아직 안 했어 = I haven’t done it yet
• 아직 안 봤어 = I haven’t seen it yet
• 아직 안 읽은 독자들 = readers who haven’t read it yet

So 아직 reinforces the idea that the reading has not happened up to this point.

독자들 means readers, and -은/는 marks the topic.

So 독자들은 means as for the readers or the readers, at least.

This helps set up the main statement of the sentence:

• 친구가... 말해 버려서 = because my friend spoiled the plot
• 아직 안 읽은 독자들은 화날 것 같아 = readers who haven’t read it yet will probably be angry

Using -은/는 here feels natural because the sentence is making a general statement about that group of people.

화나다 means to get angry or to be angry.

-ㄹ/을 것 같다 means it seems like, it looks like, or I think ... probably.

So:

• 화날 것 같아 = it seems like [they] will get angry
• more naturally: they’ll probably be angry / upset

This expression softens the statement. Instead of saying 독자들은 화날 거야 (the readers will be angry), the speaker says 화날 것 같아, which sounds more like an opinion or prediction.

Both are possible, but they are slightly different in form:

• 화나다 is the dictionary form
• in actual sentences, you often also see 화가 나다

So these can both express anger:

• 화날 것 같아
• 화가 날 것 같아

The version without 가 is very common in speech because 화나다 is often treated as a single lexical unit. The meaning is basically the same here.

The object is omitted because it is understood from context.

The sentence already mentioned 줄거리 and implies something like a book, novel, or story. So 아직 안 읽은 독자들 really means:

• readers who haven’t read it yet

In Korean, once the context is clear, objects are often left out. You do not need to repeat 그 책을 or 그 이야기를 if everyone knows what is being discussed.

It ends with 같아, so it is casual speech.

A more polite version would be:

• 친구가 줄거리를 미리 말해 버려서 아직 안 읽은 독자들은 화날 것 같아요.

A more formal/written version could be something like:

• 친구가 줄거리를 미리 말해 버려서 아직 읽지 않은 독자들은 화가 날 것 같습니다.

So the original sentence sounds like natural everyday conversation.

Yes, it could.

• 안 읽은 독자들 = more conversational and natural in speech
• 읽지 않은 독자들 = a bit more formal or written

Both mean readers who have not read it.

In casual spoken Korean, 안 읽은 is usually the more natural choice.

It breaks down like this:

• 친구가 = the friend (subject)
• 줄거리를 = the plot (object)
• 미리 = in advance / beforehand
• 말해 버려서 = because [they] went and told it / spoiled it
• 아직 안 읽은 = who haven’t read [it] yet
• 독자들은 = the readers (topic)
• 화날 것 같아 = seem like they’ll get angry

So the full structure is:

[Because my friend spoiled the plot beforehand], [readers who haven’t read it yet will probably get angry].

That is a very common Korean pattern: a reason clause first, then the main clause.