najskrytszy po angielsku:

somebody's innermost secrets / thoughts

You could find out my innermost thoughts and secrets by reading my diary, but don't you dare touch it!

This was the diary in which Gina recorded her innermost thoughts and secrets. The spacecraft will fly through the innermost rings of Saturn.

I don't expect him to understand my innermost thoughts but I wonder what I can do to get him to hold an interest.