A riveting and uncomfortable exploration. Fascinating, disturbing, and thought-provoking. Louis Theroux specialises in this sort of thing, and doesn't shy away from becoming part of the story he is telling.
His carefully cultivated air of innocent naivety gets him and his crew close enough to intimately explore the inner workings of his subjects, and this Columbo-like tactic has served him very well as an interviewer and documentarian over the years.
But when in 2000 he chose Savile as his subject, the innocence and naivety that usually got him the required dirt instead backfired and kept him from seeing and exposing what should have been obvious. Fifteen years later, this film explores Theroux's thoughts and feelings about the time he spent with Savile, and how he could have missed the signs.
In a way, the interviews with some of Savile's victims, friends, and associates, are almost redundant, as the clear focus and interest of this film is Theroux's need to understand how he was so thoroughly hoodwinked and explain himself, both as a journalist and as a man who briefly befriended a monster.
This is a highly watchable piece of filmmaking, which is for the most part honest, raw, and self aware. It doesn't sugar-coat anything, nor does it use any cheap tricks or gimmicks to over-sell the creepiness of its subject matter. Apart from a tendency towards the ominous use of sinister-looking freeze-frames, this film essentially tells its story straightforwardly. The subject matter and footage provide all the necessary thrills and chills without need of further embellishment.
All in all, a very solid piece of documentary filmmaking.