Miranda Cleaves was a 22nd century Earth acid miner who worked for the company Morpeth Jetsan. She had an inoperable blood clot in her brain. According to her own Ganger, she "always has to take charge, even if she doesn't know what the hell is going on."
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 all gained independent self-awareness. Despite the words of the Eleventh Doctor, who urged her to accept that the Gangers had become truly alive, she saw them as a threat and killed one of them, then declared war on the others. (TV: The Rebel Flesh)
Miranda followed the Doctor into the air shaft and led 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 the real Dicken. Miranda boarded the Doctor's TARDIS with the travellers and remaining miners. The Doctor gave her some medicine for her blood clot and dropped her and Ganger Dicken at Jetson Morpeth, where she was to be interviewed by reporters and campaign for Ganger rights. (DW: The Almost People)