Some of the most unbelievable parts of the show (based on the book by Dan Simmons) are true. The adventures still capture the imagination of Britons to this day. The expedition did happen. It was Franklin's third and final expedition to the Northwest Passage, the Arctic route that links the Atlantic and the Pacific.
The Reign of Terror (French: la Terreur) was a period of the French Revolution when, following the creation of the First Republic, a series of massacres and numerous public executions took place in response to revolutionary fervour, anticlerical sentiment, and accusations of treason by the Committee of Public Safety.