Brothers Rob and Andy Duncan have been diagnosed with the potentially fatal haemochromatosis where the blood absorbs too much iron subsequently putting pressure on the organs. So, of course, they decided to make a show about it.  Rather than a poignant musing on their condition, instead we get a gloriously silly play with a whole host of props seemingly gathered from a big cupboard in the kitchen. Inspired by the likes of Star Wars and Arthurian legend, they tell their story of an alien race who came to earth on an iron apparently with help from a lot of other famous ‘irons’, including Jeremy. There they find a man brought up by a deer, a holographic king and an important ‘blood sword’ in a cave.

Every now and again real life (albeit in absurd form) interjects such as the doctor’s news of their diagnosis. The sets wobble and the acting is suspect plus there’s plenty of apparent improvising. Is it deliberate? Who knows. Frankly, who cares. This is such tremendous fun, full of inventive creations such as a bin-liner leech and a very silly take on the potter’s wheel scene from Ghost. The surreal qualities are Python-esque and there are moments where the pair somehow manage to look like Terry Gilliam’s animations come to life. 

The Duncan Brothers: Blood Sword, Underbelly Cowgate, until 25 August, 9.30pm.