get to the bottom of something—
1. (also: reach the bottom of something ) reach the lowest point of smth.:
- They were resolved to renew their work in the same pit but they had scarce got to the bottom of the stairs that led to the pit.
2. explore smth. thoroughly (to determine the cause, etc.):
- We’ll get to the bottom of the problem and get your vehicle back on the road as quickly as possible.
get to the bottom of the barrel—run out of resources or possibilities:
- It seems nobody has any fresh ideas on the subject. We are getting to the bottom of the barrel.