How to understand: "he was talking about interfering with what the planets say is going to happen"?

Question

"Firenze saved me, but he shouldn't have done so.... Bane was furious... he was talking about interfering with what the planets say is going to happen.... They must show that Voldemort's coming back .... Bane thinks Firenze should have let Voldemort kill me.... I suppose that's written in the stars as well."

The sentence in bold looks ungrammatical to me. I think that sentence can be separated into two sentences:

1. he was talking about interfering with what the planets say.

2. what the planets say is going to happen.

The original one simply puts those two sentences together, which doesn't look grammatical.

Maybe, I just misunderstood it. What's the correct way to understand it?

-- Excerpted from Harry Potter.

Answer 1

He was talking about interfering with

what [i.e. that which] the planets say is going to happen.^{noun phrase}

The noun phrase there can be paraphrased as "destiny" or "fate".

I want to know
what the film director says is going to happen
if the studio cuts his budget.

P.S. I am not sure how this structure would be parsed nowadays.

To me it seems that

what ... is going to happen if the studio cuts his budget

is the base noun phrase with the film director says being a clause restricting it.

But it might be that the complement of "want to know" is the film director says with its interrogative clause complement with extraposition of what:

I want to know {the film director says [what] is going to happen if the studio cuts his budget}
I want to know {[what] the film director says is going to happen if the studio cuts his budget}

Answer 2

Dan, you have asked several questions re HP. Be aware that JK Rowling surely has an army of very qualified literary editor or editors. There is nothing wrong with that sentence, it is just long.

Here is the parse:

[...] he was talking about|| interfering with|| what the planets say|| is going to happen.

In other words, the planets say (i.e., the movement of the planets as in astrological predictions) something is going to happen and he was talking about interfering with those predictions.

Here are two more examples of this structure:

[...] they were discussing ||not abiding by|| what the authorities said|| was going to ensue.

[...] we were considering leaving what my friends called a disaster [that is] waiting to happen.