At Long Island Jewish Medical Center, a loudspeaker announces an emergency in one of the rooms. It is March 2020, and the Covid-19 pandemic has just begun to take hold in the U.S. A team of nurses and doctors in the hospital is preparing a patient for intubation. A doctor leans over the patient, whose name is Patrick George.

“George,” the doctor shouts, “do you want to be put on a respirator?”

“Put me on,” George responds weakly.

“We’ll let your family know, OK?” the doctor says.

George is struggling to breathe and knows it’s his last hope.

“Put me on now,” he says.

If you have survived the pandemic without going inside a Covid ward, you will likely be stunned by the grim intimacy of this scene and the fact that you are witnessing it, with real-time urgency, in Matthew Heineman’s new documentary, “The First Wave.” The scene offers the kind of life-and-death drama that medical staffs have staggered through every day while the rest of us rarely or never saw it. We were — and are — isolated from the traumatic realities inside U.S. hospitals as more than 750,000 souls perished from the virus.

This opening scene, not yet 30 seconds long, twists in ways you cannot forget.

A nurse puts a phone, encased in a plastic bag, in front of George’s face. On the other end, seeing him via FaceTime, is George’s wife.

“I love you, baby,” she cries out.

“I love you too,” George responds.

“OK, be strong.”

“Bye,” George says.

“I love you,” she repeats.

“Bye bye,” George says. “Bye bye bye bye bye bye.”

This scene is not done with us but I won’t say what happens next. What I can say is that “The First Wave” is necessary to watch. Unless you have already seen and heard the kinds of events it shows, you have an incomplete understanding of the pandemic and of what three-quarters of a million deaths mean — when instead of a statistic in a news story, the casualties are a man on his back, his wife on the phone, and the nurses and doctors doing everything they can to save his life.

The saving grace of this film, if that’s the right way to put it, is that it journeys around the epidemiological trenches at this New York City hospital and brings back a variety of stories, some of them uplifting, and they thread into an effective narrative. There are patients who seem on the verge of death and struggle back, there are family members urging them along on those plastic-encased phones, and there are medical staffers whose trauma-filled work is getting the attention it deserves in our less troubled lives.

It sounds strange to say, but there is art in this film too. The way the camera lingers just long enough at the right moments and not too long at others, the way the lifted brow of a nurse speaks louder than words, the way the film breaks out of Long Island Jewish and moves into the streets of New York City, taking us from the gasps of Covid patients to the “I Can’t Breathe” chants of the Black Lives Matter movement — this is masterful work.

Heineman is no stranger to documentaries. He directed the Academy Award-nominated “Cartel Land,” about the drug trade on the U.S.-Mexico border. He also directed “City of Ghosts,” an award-winning film about citizen journalists in Raqqa, Syria. Those films demonstrated a willingness and ability to work in dangerous areas and gain the confidence of people who otherwise might not let an outsider into their worlds. Those talents are what went into the making of “The First Wave.”

Heineman used his experience and contacts to gain unparalleled access to Long Island Jewish. Across the U.S., hospitals were shutting their doors to journalists as the pandemic began. Only a handful gained entry, and their visits were short, usually just a few hours or a few days at most. Heineman’s team was at Long Island Jewish for months. Hospital administrators have cited safety and privacy concerns for keeping journalists out, but as Heineman’s experience showed, they could work inside Covid wards without getting in anyone’s way or spreading the virus.

That’s what makes the footage in his documentary so extraordinary. I worked for months on an investigative article that delved into the way hospitals cracked down on reporters in the U.S., and I spent a lot of that time scouring through the imagery that was published by journalists, including filmmakers, and by medical staffers (some hospitals even threatened doctors and nurses who shared photos or videos). I’ve seen nothing that comes close to Heineman’s graphic portrayal of Covid victims.

The only visual documentation of the pandemic that’s in the same league comes from far away. The director Hao Wu, working with Chinese journalists in early 2020, got relatively unfettered access to four hospitals in Wuhan, where the virus originated. His powerful documentary, “76 Days,” came out last year and won an Emmy. Until the emergence of Heineman’s film, which opened Friday, Americans who wanted a visceral look inside a Covid ward had to watch a film shot in China.

It is hard to categorize “The First Wave” because it crosses boundaries: It is a documentary that also feels like a horror film, an exposé of social injustice, and a love letter. In its review of “The First Wave,” the Washington Post has a line that manages to be insightful and off-kilter at the same time. “The film feels like a viscerally effective time capsule from the recent past,” wrote Michael O’Sullivan, “yet one whose arrival in theaters may still be too soon for many.”

A time capsule is filled with the familiar objects of a civilization. But what’s in “The First Wave” is unfamiliar to most of us; we have not seen it before and perhaps have been unable to imagine it. There is the anguish of patients as they labor to breathe, the medical instruments warning of hearts no longer beating, the body bags zipped up and hauled away, and the moments of silence before nurses rush to the next room to try to save another life. Stumbling onto this time capsule, we are visitors from another world who are seeing for the first time what the Covid pandemic really meant.

This film has not come too soon. It has come too late.