The Red Stain (2018)

Young American Billy brings a red-stained shirt to the dry-cleaning business of an elderly Italian couple. After he leaves, they spend hours spinning increasingly intricate, improbable yarns about the origin of the stain. This, in turn, leads them to wonder about Billy's identity. Is he a hot-blooded lover in the midst of an affair? A super spy? A chess-boxing champion? All of these, perhaps? And why did he venture abroad in the first place?