How do you capture the embers of a revolution? The transfixing “Get Out” star Daniel Kaluuya and Chairman Fred Hampton Jr. undertake such a promethean effort in Shaka King’s crime-suspense biopic “Judas and the Black Messiah.” Recounting the brief life of Fred Hampton, the Chairman of the Chicago chapter of the Illinois Black Panther party, through the eyes of the man who would betray him, “Judas and the Black Messiah'' explicates the FBI’s efforts to stunt the young speaker’s political ascent, leading to his assassination. But the reverberations of Hampton’s truthful voice, as an adroit community leader and an explosive, robust orator, have not diminished. “Judas and the Black Messiah,” at its best, is not just a relitigation of a murder. With King’s provocative camerawork, a sterling cast that includes Kaluuya's electric performance, and the support of Chairman Fred Jr and his mother Akua Njeri (formerly Deborah Johnson), the biopic delivers his legacy to the present generation.