Doctor Who (2005) (2005)

S10E10 The Eaters of Light

In the distant past, the ninth legion of Rome mysteriously disappeared in the Scottish highlands. Bill proposes a theory regarding their fate, and the Doctor possesses a time machine to investigate. Upon reaching ancient Aberdeenshire, they uncover a peril far more alarming than a lost army. Hidden within a cairn on a hillside lies an ominous portal that could lead to the destruction of the world.