im not usually big brain enough to be a comeback-theory-nevie and idle usually has multiple themes/inspirations for their cbs but i think this one might be in part based on the japanese short story Barn Burning by Haruki Murakami which was adapted into the korean film Burning

[spoilers on these two ahead]

basically the story is about a man who reconnects with an old friend and starts a bit of a relationship with her but she leaves on a trip for a few weeks and returns with a mysterious bf. they all spend an evening at the mans home and +

after she goes to bed the bf tells him that every two months or so he likes to burn barns, and hes gonna do it again soon cuz theres a lot on nice barns near the mans house. so after that evening, he starts spending more and more time looking out for the barns to try to save them

but he never finds one burned. weeks later he meets the bf at a store and asks him about the barns, which the bf says he did burn one weeks ago. and asks if hes seen the girl lately, which neither have, and so he goes to her house to find out she hasnt been there for weeks

and you slowly come to realize that shes disappeared and the bf's "barn burning" is a metaphor for murder.

the theme of burning + minnie saying "we'll vanish" + the gf having a theme of a butterfly makes me think idle are the victims of the 'burning' man

anyways lets all pretend this theory is as good as the rest of urs..gj bob great theory