Zac Efron says ‘The Iron Claw’ is a special film because the cast’s chemistry was “off the charts”. The 36-year-old actor plays Kevin Von Erich in the biographical sports film about the professional wrestling family the Von Erichs, directed and written by Sean Durkin. Zac stars in the movie with Jeremy Allen White, Harris Dickinson, and Stanley Simons, and he quickly got the feeling that they were all contributing to something remarkable because of their commitment to the true story. He told website HeyUGuys: “We got to know each other really well before we got started and you could tell that …