Board Thread:Questions and Answers/@comment-16749030-20131226052855/@comment-3361105-20140129222633

The only one you need to read to understand the story is.

Everything else is just side-stuff where the Joker attacks the bat-kids.

In my opinion, the ones most worth reading are Batgirl's story and the Red Hood story.

For everyone else, the crossover is pretty much "Joker shows up, beats the kid, kidnaps them, TO BE CONTINUED IN BATMAN #17!!!"