This episode is just great and has so many elements which make it a top tier episode for me. Capaldi is excellent in this story despite his presence in the story being limited. Coleman shines as an impersonating Doctor and the supporting cast, most notably Rigsy are interesting additions and contribute well to the story and don't feel shoehorned in. The monsters are unique and geniunely scary and their creepiness is always going to give me at least a few chills. There is well placed humour throughout the story and a natural and well executed series arc development. It's in the top 10 maybe in top 5 of my favourites in the show.
Review of Flatline
