This idiom or expression has to do with:

Leaving someone on his (or her) own.
Leaving someone behind to take the blame.
Abandoning someone who is in need of help.

Note:
As this is done by people who know each other, the person who’s left behind feels betrayed.

A. Why are you so upset with me?
B. You left me hanging out to dry!! You didn’t even TRY to help!

Also:
Leaving someone behind.