get to the bottom of something
get to the bottom of (something)
To determine the cause or source of something or solve the mystery of something. What is causing this water leak? Has anyone gotten to the bottom of it yet? I have every confidence that our detectives will get to the bottom of this crime.
get to the bottom of something
COMMON If you get to the bottom of a problem or mystery, you discover the truth about it. The attack was quite severe. We intend to get to the bottom of things and, if needs be, ensure that action is brought against those responsible for it. The secrets of a truly happy couple are ultimately a private mystery, but we've tried to get to the bottom of it.