I Need to Know

haber is an interesting verb with many different auxiliary uses.

One is the haber de + infinitive construction:*

*Used in speech almost exclusively in Spain.

"Get out of my house." 

"You're not well, Nick.  I know you.  I need to know why you're trying to destroy Matt Murdock."  He stops upon hearing the name.  I smell his guilty sweat.  

I notice the heat in his cheeks…an attack of rage.  He prepares to strike...

Notes:

sal (from salir) is an irregular imperative (cf. haz, ten, pon, etc.)

Haber de conjugates normally and functions in a similar way to tener que and haber que, although the sense of obligation may seem a little weaker:

Ha de estar aqui.  He should be here.
He de estudiar. I should study.

al + inifitive is used to express "as soon as" or "upon"