12. Nightmare in Silver

Hedgewick's World of Wonders was once the greatest theme park in the galaxy, but it's now the dilapidated home to a shabby showman, a chess-playing dwarf and a dysfunctional army platoon. When the Doctor, Clara, Artie and Angie arrive, the last thing they expect is the re-emergence of one of the Doctor's oldest foes. The Cybermen are back!