The escalating supernatural horror and existential threat posed by Broton's Zygon forces and their sonic weapons technology, targeting both human forces and the Doctor himself

Munro’s frantic attempts to raise Hibernian Control are drowned in electromagnetic screech before being torn apart by the rig’s structural failure. His Mayday cuts off mid-breath in a violent explosion …

Broton and the Zygon operator observe the Doctor on their ship’s monitors while he analyzes a monstrous force threatening the oil rigs. Recognizing the Doctor’s intellect and growing knowledge of …