Idiom Definition:
"to get to the bottom of something"
to investigate and thereby discover the basic underlying meaning or purpose or reason for something
Synonyms:
appreciate, apprehend, catch, clarify, comprehend, crack, decipher, decode, divine, fathom, find, figure, get, grasp, have, hit, interpret, know, penetrate, perceive, puzzle, reason, recognize, savvy, unlock, unravel, untangle, work