Matt Bomer, Mark Ruffalo Matt Bomer, Mark Ruffalo

If The Normal Heart, which premieres Sunday at 9/8c on HBO, were a work of fiction, it would be tragic. But knowing that it's rooted in actual events makes it nothing short of devastating.

Based on Larry Kramer's 1985 play (which was revived on Broadway in 2011) and adapted for the small screen by Ryan MurphyThe Normal Heart takes a brutal, unflinching look at the onset of the AIDS epidemic in New York City in the early 1980s. The story is told through the eyes of a group of activists who founded the organization Gay Men's Health Crisis to help patients living with the disease.

At the forefront of the fight is Ned Weeks (Mark Ruffalo), a character based on Kramer himself, who's tasked with delivering a message no one in his community wants to hear: that one solution to the growing problem may be refraining from sex. At least that's the opinion of the no-nonsense Dr. Emma Brookner (Julia Roberts, in one of her strongest performances to date), a wheelchair-bound physician, herself a victim of polio, who's seen more than half her patients die from the mysterious illness. With the benefit of hindsight, the hostile counter-argument to her opinion — that promiscuity is a political statement by the gay community — is crushingly naïve.

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Ned's colleagues at GMHC include the organization's brash, blonde and closeted president Bruce Niles (Taylor Kitsch, who's excellent in a role that's quite a departure from his career-making turn as Tim Riggins on Friday Night Lights); city worker Mickey Marcus (Joe Mantello, who played Ned Weeks in the 2011 play); and sweet, sassy Southerner Tommy Boatwright (Jim Parsons, in the same role he played on Broadway). Along the way, Ned also meets and falls in love with Felix Turner (Matt Bomer), a New York Times reporter who struggles to persuade his colleagues to cover the epidemic.

Ruffalo turns in an Emmy-worthy performance as the stubborn, fiery Ned — who spends most of the movie so consumed by frustration and rage that he looks as if he might explode at any moment. The angry passion Ruffalo puts on display in scenes where Ned rails against government officials, his colleagues at GMHC, and even his own brother (Alfred Molina) is matched only by his vulnerability in the tender scenes he shares with Bomer, whose physical transformation as Felix becomes a patient of Dr. Brookner is simply astonishing. The two actors shine together, and it's the relationship between Ned and Felix that gives the movie its true weight.

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In Murphy's hands, The Normal Heart is a tour de force. The Glee and American Horror Storycreator thankfully refrains from his usual campiness here, and instead relies on more muted moments between friends and lovers to pack the most powerful punches. Yes, there are plenty of bodies on display throughout, and in varying degrees of nudity, but Murphy's purpose is not (entirely) titillation. Rather, the contrast between seeing young men in their prime, reveling in a hedonistic Fire Island beach weekend at the start of the movie, and in subsequent bathroom scenes as the ravaging effects of the disease take their toll is successfully jarring. Per usual, Murphy's musical choices, while not subtle — "I Will Survive" plays over a club scene early on, while the movie ends with Simon & Garfunkel's plaintive "The Only Living Boy in New York" — are also hauntingly effective.

The Normal Heart is an important film, one that's both a touching tribute and a cautionary tale. Despite advancements in the treatment of HIV and AIDS that would have seemed unthinkable at the time the events depicted took place, the movie concludes with the chilling reminder that 36 million people worldwide have died from AIDS, and more than 6,000 new people are infected with HIV every day. As an examination of a pivotal point in history, the film preserves the memories of thousands of people whose lives are gone but must not be forgotten, and will break more than a few hearts in the process.

The Normal Heart premieres Sunday at 9/8c on HBO. Watch the trailer below: