Training Day.
After Bats saves her life (the rope would have torn her arms off), the talk to her in the batcave. To see if she's good enough to join them. She fails the test by one mistake -- "killing" one of the targets. However, Robin supplies her with Bat-supplies, telling her that Bats will come around to having her officially join them.
I'm enjoying this series. I wonder how the other half goes!