Dr. Wu was a doctor at a Gotham City hospital.
Dr. Wu had treated one of the Scarecrow's thugs who had been trying to poison a spa's drinking water with gas. The thug had been exposed to the toxins when Batman stopped him. She ran some tests on both the thug and Batman, and found that he was also exposed. Since he breathed in less of the gas, it took longer to become effective. Dr. Wu provided him with an antidote that would sedate him for two full days. Driven by the need to hunt down the Scarecrow, Batman ignored Dr. Wu's instructions to rest and took off with the antidote.