“The Thread” is a pioneering documentary that reveals the significant influence that amateur online writers are exerting on modern journalism. In the aftermath of the 2013 Boston Marathon bombing, amateur detectives on platforms like Twitter and Reddit embarked on a mission to uncover the culprits. This crowdsourced investigation mistakenly implicated an innocent young man, fundamentally altering the landscape of journalism. The film is directed by Greg Barker, known for “Manhunt,” and is executive produced by Emmy Award winner Jonathan Chinn, recognized for “American High,” and Academy Award winner Simon Chinn, known for “Man on Wire.”