Rarely does a music documentary so vividly evoke both the artistic approach and the tricky personality of its subject. A portrait of the great prog rock ensemble King Crimson, purveyors of aggressively complicated guitar noodling, duelling time signatures and, you suspect, numerous nervous breakdowns among its members, the film is angular and abrasive, exacting and playful, extremely funny and achingly melancholy.

Although largely outside the frame, director Toby Amies (The Man Whose Mind Exploded) becomes a character in the film: part confessor, part lightning rod for the sparking tensions in the band, most of which emanate from the brilliant, tyrannical Robert Fripp. In cinemas for one day only, this is well worth seeking out.

• In cinemas 19 October only; streamed event 22 October via nugs.net