Subterrestrial's "H-21" is inspired by early 20th century exotic dancer Mata Hari, who was executed for treason in France during World War I after being accused of spying for Germany. Subterrestrial uses harsh, POKEY and TIA noise and heavily aliased exotic rhythms to explore her often violent life and tragic death. It is believed that she was wrongly accused of her crime and made a scapegoat. H-21 was her alleged codename.