In The Beginning

"In The Beginning" is the first episode in the eighth season of Doctor Who, featuring the first appearance of the Twelfth Doctor and his companion Billy O'Hara.

Synopsis
The Doctor, fresh from regeneration, crash lands in Dublin after receiving a distress signal. There he meets unemployed Billy while tracking a Charth scout, soon realizing that the Charth fleet hangs invisible over Earth. With the help of Billy he foils the Charth invasion plan, and offers Billy to accompany him in the TARDIS.