After an explosion, the Doctor realises that Middleton is located in an ancient volcanic caldera - with a new eruption about to start. The Doctor meets the army on the way to pick up their new guns, where they are attacked by magma creatures and the new guns explode when fired, killing most of the soldiers.
After an explosion, the Doctor identifies that Middleton is situated in a dormant volcanic basin - with a fresh eruption imminent. The Doctor encounters the military on their way to acquire their novel ordnance, where they are attacked by lava creatures and the new guns detonate when fired, killing most of the soldiers.