Doctor Who

A nuclear missile convoy faces an unexpected threat when knights in armor clash with modern weaponry near an archaeological dig. The Doctor, along with Brigadier Lethbridge Stewart and Ace, finds himself embroiled in a battle against a demon known as the Destroyer. As Ace retrieves a powerful sword from a submerged spaceship, they must uncover why the knights call the Doctor 'Merlin' and prevent Morgaine from destroying the world.