“The world is a fine place
And worth the fighting for
And I hate very much to leave it”
— Ernest Hemingway, “For Whom the Bell Tolls”

That quote kick-starts “John McCain: For Whom the Bell Tolls,” the HBO documentary so titled because that is McCain’s favorite book — and because as the world knows, the 81-year-old McCain has a very aggressive form of brain cancer, and as he readily acknowledges, the bells will soon toll for him.

We know the story of John McCain at least as well as we know the stories of all the presidents that have served in McCain’s lifetime.

We know about McCain following his four-star admiral grandfather and his four-star admiral father in the United States Navy, and we know about his heroic service to the country in the Vietnam War and the five and a half years he spent as a POW.

We know about the ups and downs of his multiple terms in the United States Senate, and his unsuccessful runs for the presidency.

We know about his personal life. The good, the bad and the ugly.

Still, with all we know about this singular American figure, “For Whom the Bell Tolls” is a remarkable portrait of a remarkable man — an insightful, poignant, journalistically sound profile that gives McCain his due, but steers clear of hagiography.

When the ex-wife and the formerly estranged grown children appear on camera and speak with candor, when the subject of the biography talks frankly about some of his biggest political and personal missteps — that’s a warts-and-all picture.

“I have lived an honorable life, and I am proud of my life,” says McCain. “[But] I haven’t always done the right thing.”

We first see McCain on his ranch in Arizona in the summer of 2017. He says all he asks of his doctors is to not hedge about telling the truth: “It’s just bull—- [when they do that], and it drives me crazy.”

Soon we flash back to McCain’s youth, from his birth at the Coco Solo Naval Air Station in the Panama Canal Zone to his time at the Naval Academy and then his service in Vietnam. (With McCain coming from Navy royalty, there’s a relative bounty of archival footage of him as a young military man.)

McCain speaks in clear and measured tones about the circumstances of his capture in 1967.

“During that period of time, they decided to escalate the air war over North Vietnam. We started striking targets inside Hanoi. … A missile took the wing off the airplane, so I ejected. When I hit the airstream, it broke my arm and also my leg.”

As the Vietnamese dragged McCain out of the water, he notes, “One of them stabbed me with a bayonet, another smashed my shoulder.”

In a 1965 photo seen in "John McCain: For Whom the Bell Tolls," Navy pilot McCain (right) is seen with his squadron and T-2 Buckeye trainer.

In a 1965 photo seen in “John McCain: For Whom the Bell Tolls,” Navy pilot McCain (right) is seen with his squadron and T-2 Buckeye trainer. | HBO

We see news footage of McCain’s then-wife reading letters from her POW husband. In present day, Carol (described by the filmmakers as “Former Wife”) talks of getting the call about her then-husband being captured. Doug McCain describes coming home from school and learning his father had been shot down. Some 50 years later, you can hear the pain in their voices.

We hear the excruciating details of the torture inflicted on McCain for years. YEARS.

Eventually, McCain signed a propaganda “confession.”

“I will be ashamed and embarrassed about that for the rest of my life,” he says.

The doc includes a fascinating passage about McCain’s evolving views on Vietnam and his relationship with fellow veteran but political opposite John Kerry, and some blunt talk about the disintegration of McCain’s marriage to Carol.

“He was looking for a way to be young again,” Carol says of John’s affair with Cindy, who eventually became his second wife. “I was blindsided, and it broke my heart.”

There’s also a segment about the Keating Five scandal of the 1980s. So no, “For Whom the Bell Tolls” does not shy away from McCain’s missteps through the years.

Some of the most positive sound bites in the film come from political opponents, including Kerry; McCain’s good friend Joe Biden; Bill and Hillary Clinton, and Barack Obama. It’s a reminder that not so long ago, Democrats and Republicans actually were civil to one another and respected one another.

“I know this is a very vicious disease,” says McCain of his condition. “I greet every day with gratitude …

“I’m also very aware none of us live forever. … I’m very grateful for the life I’ve been able to lead. And I greet the future with joy.”

Would that we all go so nobly into that good night.

★★★1⁄2

Kunhardt Films presents a documentary directed by Peter Kunhardt, George Kunhardt and Teddy Kunhardt. Running time: 104 minutes. Premieres at 7 p.m. Monday on HBO, HBO NOW and HBO GO.