Despite all the levitating superheroes, this third installment in Marvel’s Captain America franchise almost sinks under the weight of its own gravitas, especially during the largely expository first hour. After unintentionally killing innocents during a mission in Africa, the Avengers must vote on whether to accept oversight by a United Nations panel; Iron Man (Robert Downey Jr.) leads the supporters, and the naysayers line up behind Captain America (Chris Evans). The players salvage this thing with their acting and awesome thighs, and the fun really kicks in when Spider-Man (Tom Holland), Ant-Man (Paul Rudd), and Black Panther (Chadwick Boseman) join the squabble in an exhilarating airport sequence. After that centerpiece, the slugfest grows monotonous on its way to a final showdown. Brothers Joe and Anthony Russo directed.