The basic mythology is that someone — maybe frontrunner Hillary Clinton, maybe the Republicans, maybe her billionaire backers, maybe even the FBI — is using Black Lives Matter to tear Sanders down, to diminish an insurgent candidacy that, the supporters say, is viewed as a real threat by the establishment.

On a flight from San Francisco to Phoenix recently, for instance, a young, white, male Sanders supporter noticed the reporter sitting next to him was writing about Sanders and, unprompted, started talking about information dug up on Marissa Johnson, one of the young black women who took the stage at the Seattle Social Security event. He noted online sleuths on reddit had discovered the woman had posted about being an evangelical Christian and a Sarah Palin supporter on Facebook years earlier. Subterfuge, he said. She’s not the real deal. Something’s afoot.

Black activists like Johnson who have interrupted Sanders on stage have been doxxed, digitally harassed, and shouted at by Sanders backers, they say. Online there is the vibrant talk about who is really, secretly, responsible. The activists laugh off specific conspiracy charges but say that the continued incredulity from Sanders’ white supporters toward their cause prove their point that “white progressivism” isn’t interested in the issues Black Lives Matter is trying to bring to the fore. The lasting conspiracy narrative is all the proof they need, the activists say.

Hours after the first reports of the Seattle action — in which a small group of activists took over an event where Sanders was set to speak — the internet lit up with people claiming there was something amiss.