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)
Miranda followed the Doctor into the air shaft and lead them to the Evac Tower. Cleaves's Ganger redirected the shuttle to the courtyard, via the password "BADBOY." Cleaves lost communications with the mainland and had to follow the Doctor, along with Ganger Jimmy, Ganger Dicken and Real Dicken. Miranda boarded the Doctor's TARDIS with the travellers remaining miners. The Doctor gave her some medicine for her blood clot and dropped her and Ganger Dicken at Jetson Morpeth to be interviewed by reporters and campaign for Ganger rights. (DW: The Almost People)