The Fifth Ark

Synopsis
The Doctor takes Christina to the set of her favorite movie: Indiana Jones and the Last Crusade in the ancient city of Petra, where The Doctor realises the prop for the Holy Grail is far too realistic. Following a trail of alien activity, The Doctor, Trevayne and Christina embark into the ancient tombs with Harrison Ford and Alison Doody, where they stumble upon the Fifth Ark, an ancient alien race, and a weapon edging Earth closer to its final war.