Miranda Cleaves was a 22nd century Earth Acid miner. She had an inoperable blood clot in her brain.
Like most workers in hazardous conditions, Miranda and her co-workers used Gangers as surrogates. When a bolt of solar energy struck the facility, the Gangers were all given independence. Despite the words of the Doctor, who urged her to accept that the Gangers had become truly alive, she saw them as a threat, and killed one of them, before declaring war on the others. (DW: The Rebel Flesh)
