“To win a war, you have to start one.” This HBO telefilm arrives nearly three decades after Larry Kramer’s play premiered off-Broadway. Mark Ruffalo, Matt Bomer, Taylor Kitsch, Jim Parsons and Julia Roberts star in the adaptation directed by Ryan Murphy and scripted by Kramer. Set in NYC during the onset of the HIV/AIDS crisis of the early ’80s, The Normal Heart follows gay activists and their allies in the medical community as they try to expose the truth about the burgeoning epidemic. HBO already is looking into a sequel. The telepic, which co-stars Alfred Molina, Joe Mantello, Jonathan Groff, Denis O’Hare, Stephen Spinella, Corey Stoll, Finn Wittrock and BD Wong, bows May 25 on the premium channel. Here’s the first full trailer: