Wiktionary
vb. (context idiomatic English) To understand, discover the truth about, or solve.
Usage examples of "get to the bottom of".
But you should ask for police protection till we get to the bottom of this.
So why not use your investigatory drugs on this jerk and get to the bottom of it?
We shall be with you within an hour of receiving it, and we shall then very soon get to the bottom of the business.
The sooner we do it the better, and get to the bottom of this horrible affair.
If, on the other hand, it is systematic, I have no doubt that we shall get to the bottom of it.
I think that if we apply some pressure we might get to the bottom of this theft at the college.
It will be just as well for you to get to the bottom of this affair, and find out whether it is a chance meeting, or whether any of your own people have been in league with him.
Don't you see I want to get to the bottom of this as badly as you do?
But something was going on here that he was going to get to the bottom of.