Turmezistan was a nation on Earth. During the Zygon rebellion in the 21st century, the rebel Zygons from the splinter group Truth or Consequences had a training camp hidden in a town in Turmezistan. The Zygons had replaced everyone in the town, and imprisoned Osgood there after they captured her.
UNIT dispatched the Twelfth Doctor and a strike team to rescue Osgood and negotiate peace. However, the rebels lured the UNIT soldiers into an ambush by impersonating their family members, killing them all before escaping. The Doctor found Osgood hidden inside the town church and fled with her as UNIT bombed the town. (TV: The Zygon Invasion)