Must needs.

[HiirNoivl]

Needs is being used as an adverb.

We don't use "needs" as an adverb any more, but people used to. The word "needs" has been replaced with "necessarily".

So you can read that sentence as "But first we must necessarily find out all we can."

[Conradus]

Needs is being used as an adverb.

We don't use "needs" as an adverb any more, but people used to. The word "needs" has been replaced with "necessarily".

So you can read that sentence as "But first we must necessarily find out all we can."

Hiir is correct. "Must needs" may be unfamiliar to you, and it may be somewhat archaic, but it is perfectly correct and, indeed, well suited to the tone they are trying to create.

"And he must needs go through Samaria." --John 4:4, King James Version

Clown: My poor body, madam, requires it: I am driven on by the flesh; and he must needs go that the devil drives. --All's Well That Ends Well, Act I, Scene III