"Under the Hood, Part 4 of 4: Bidding War"
*Red Hood tries to negotiate with Black Mask, initially demanding fifty million dollars for the kryptonite, before settling on a more sensible price. Black Mask, of course, has no intention of paying for it, and sends Mister Freeze and a few hired guns to take care of Red Hood. However, they are expected, the hired guns are killed and Mister Freeze is getting very cross by the time that Batman and Nightwing arrive on the scene. Both Red Hood and Mister Freeze make a getaway, though the kryptonite is recovered. And now that Red Hood has discovered how things stand in Gotham, he takes the time to do something he's been wanting to do for a while. He tracks down the Joker and beats him with a crowbar, before revealing his identity. He is Jason Todd, the former Robin killed by the Joker some years ago... *Source: DCUGuide.com