It might be hard for the last one out to please turn off the lights if the lights aren’t on to begin with.

PBS Frontline’s harrowing and affecting exposé Blackout in Puerto Rico (airing Tuesday, May 1, 10 p.m., ET) will likely fall on deaf ears with the decision makers who’ve already made their decisions, right or wrong, but that doesn’t make Blackout any less urgent — or important — as an informative, eye-opening piece of television.

It’s hard to believe in 2018 that, seven months after hurricane Maria tore through the unincorporated territory of Puerto Rico in the northeast Caribbean — population 3.5 million, as of July 1, 2015 — the lights are still out over large swaths of the island.

Those looking for a bash-the-Trump-administration polemic are liable to be disappointed, though. In the tradition of Frontline’s finest news program, Blackout explains, point-by-rain-soaked-point, what happened to the island’s infrastructure, why it happened, and where things go from here. Facts may be unfashionable these days, but when Frontline is at its very best — and Blackout is at the high end of Frontline programs — facts count for everything.

First fact, little more than five minutes into the program, comes from NPR correspondent Laura Sullivan, who spent seven months poring over detail in the wake of Hurricane Maria — this, after she had already reported on Hurricane Irma and the flooding in Houston a month earlier. Sullivan hitched a helicopter ride with Lt. Gen. Jeffrey Buchanan, (right) head of the U.S. Army Maria response team ferrying supplies to stricken towns along Puerto Rico’s northeast coast a full month after Maria flattened Puerto Rico’s infrastructure.

Military rescue teams don’t deal in opinion, and they have little time for politics. The only thing that interests Lt. Gen. Buchanan is getting the job done, and 30 days after the hurricane, the job is not getting done.

This isn’t about a power blackout, Buchanan informs a clearly startled Sullivan. This is about water. Drinking water, Clean water. Ferrying bottled water in, as fast as they can, in as much bulk as they can. Getting the power on can wait.

“The short term, from my perspective, is really all about water,” he says, with the clipped, plain-spoken bluntness of a career soldier. “We’ve been distributing food, but many places have plenty of food. People need clean water to be able to drink and survive.”

“I thought this was about power,” Sullivan says.

“Nope,”  Buchanan replies. “Power is the long term.”

Power is critical to long-term thinking, he adds, because the water problem is directly related to lack of electricity. In the short term, it’s all about getting clean water to people who need it now.

Down the road, power is needed to fire up the generators that ensure a steady supply of clean water weeks, months and years after the disaster has hit. And that, as Blackout explains over the next hour, is why the situation is such a mess today, seven months after the fact,

As Jesús Marquez Rodriguez, mayor of the coastal town of Luquillo, tells Sullivan, it’s an ongoing crisis that will continue for as long as the power remains as unreliable and inconsistent as it is today.

“We need electric generators,” Rodriguez tells Sullivan. “Seven generators.”

Just seven generators.

So . . . what’s the problem?

And this is where Blackout tells its harrowing tale, a tale so weird and hard-to-explain — let along justify — that it almost beggars belief.

Generators don’t grow on trees, a FEMA official implies. Also, Puerto Rico is an island. The horror! Who knew?

What do you do when 60,000 power poles come down like crumbling matchsticks? The entire electric grid — rusty and antiquated even before the storm hit — is held together, almost literally, with duct tape and bailing wire. “Gimme a break!” Sullivan is heard to say, in exasperation. Hurricane Maria is a combination of two disasters — one natural, one man-made. Rust never sleeps.

As Blackout tells its harrowing yet endlessly fascinating story, it becomes more evident that what the island really needs is more of the clear-eyed focus and military precision of a Lt. Gen. Buchanan, and less gas-bagging in Washington, DC. Rolls of paper towels tossed into a crowd at a photo op — what’s that all about? — just won’t cut it. And neither will 12,000 tarps for an island population of 3.5 million.

Sullivan takes a look at the islands history, from Columbus — “What a rich coast!” he’s purported to have said, giving the island its name — to, more recently, Wall Street banks and hedge fund managers who took one look at Puerto Rico and saw investment opportuntieis coupled with tax exemptions, bait for investors with pensions and mutual funds in tow. Like a bad episode of Billions, Puerto Rico became a laundromat for funny money, but without the Cayman Islands’ sexiness or PR profile.

Hard as it may be to believe, not one investment bank would agree to talk to Frontline, Sullivan notes. And,

Somehow, in all that moving around of money, no one saw fit to shore up Puerto Rico’s aging infrastructure. Over a period months, then years, then decades, the incorporated territory of Puerto Rico became a disaster waiting to happen — literally. Follow the money. All it would take was one decent-sized storm.

And on Sept. 20, that storm hit. Category 4 hurricane Maria — a Category 5 storm when it flattened the island of Dominica just two days earlier — wreaked its terrible havoc.

“I’m not satisfied with the level of response that it’s taken to get people electricity,” an  contractor tells Sullivan late in the program, today, seven months after Maria hit. “However, when you understand the level of devastation and the fact that (the grid) was 40- to 45-years-old, broken already by a couple of other storms—“

How is any of this okay, Sullivan demands to know.

There no easy answers.

The bottom line is the bottom line: At the end of the day, 3.5 million Americans are still at risk of losing their power at a moment’s notice. Seven months after Maria, 100,000 Puerto Ricans are still without power of any kind, and the island is still experiencing outages.

Oh, and one more thing. A new hurricane season starts a month from now, around the time The Voice will announce a new winner and families flock to the beach for the Memorial Day weekend.