The Joker manipulated her into baiting Jason into a trap. Upon learning that the Joker intending on killing Jason, Sheila had a change of heart and sacrificed herself in an effort to save Jason's life. Her efforts failed however, both her and Jason still "died". It was reveled years later when Jason Tood was the Red Hood that it was not his real mother that had died in explosion in Africa. It was revealed in 2005 or 2006 in the Batman series years later.