You’ve probably never heard of Gareth Jones. You’ve certainly heard of the writer he inspired, and the classic dystopian novel that writer created. You were forced to read it, or at least the Cliff’s Notes, in high school. But shorn of its context, that novel lacks the full punch it could deliver. Mr. Jones (2019), starring Peter Sarsgaard and James Norton, directed by Oscar nominee Agnieszka Holland and written by Andrea Chalupa, provides that context in a must-see film. Mr. Jones is powerfully relevant today, even more than when it premiered in 2019. You have undoubtedly heard of “cancel culture,”...