It was spring 2014 in the Florida Keys, before the air got sticky and the bugs showed up.

The creative trio known as KZK was less than a week into shooting their Netflix series, Bloodline, when they realized they'd struck gold.

"It made us giddy," Glenn Kessler says of the moment he shared with his co-creators: Daniel Zelman, a pal since their Hasty Pudding days more than a quarter-century ago at Harvard, and his own younger brother, former Sopranos writer Todd A. Kessler.

The trio was coming off Damages, their white-collar legal thriller that ran for three seasons on FX and then two more on DirecTV’s Audience Network.

Bloodline, the trio's follow-up project, had sparked a flurry of offers, none sweeter than Netflix's 13-episode commitment. The deal was done before a single script had been written, thanks to a pitch about a Florida Keys family and the havoc that ensues when the black-sheep big brother comes home.

Expectations spiked when KZK convinced their dream casting choices, Sam Shepard and Sissy Spacek, to play the family's haunted patriarch and nurturing earth mother. But it was a scene in week one — when all four adult siblings share the screen for the first time — that thrilled the showrunners.

"It's not like it was improvised," Glenn says of the scene, which features Linda Cardellini and the actors who play her big brothers — Kyle Chandler, Norbert Leo Butz and, as the black sheep, Ben Mendelsohn — discussing seating arrangements at a family party.

"But these four were so clear about their characters that there are stretches of that scene where all four are on camera and every performance is totally alive. Everybody's personality is distinctly drawn. It's like they'd known each other for years."

After Damages, KZK had to figure out what to do next, and the notion of family kept coming up. Zelman has been discussing the topic with the Kessler brothers for years, ever since brother Glenn auditioned for Zelman's improv comedy group at Harvard.

He later discovered just how much he had in common with the Kesslers: they all had two brothers, fathers who were doctors, and parents married more than 50 years. Plus, Zelman and Glenn both had become trained actors.

"Over the years we've found ourselves talking a lot about family and how family dynamics have changed — or not changed — as we've gotten older," Zelman says.

"As we've hit our 40s," Glenn adds, "our understanding of our family dynamics has begun to change. And because we all come from families with three sons, we recognize the roles we play. It's something we'd been talking about. So the thought was, why not try to mine some of that in our creative life?"

The Kessler brothers and Zelman had no interest in a straightforward family drama. They wanted to create a project with the kind of edge and specificity that would attract a premium cable network — or Netflix.

So they decided to make the kind of series they'd never seen before, taking the elements of a family drama and turning them into a thriller where the threat isn't external — it comes from within.

"It's not that deep, dark family secrets are revealed," Todd says. "It's more that now, with age, they're looking at [events] from a different perspective and trying to remember what really happened back then. 30, 40 years later, they're still living it out. It's like trying to wind the clock back to those moments, only to discover that it goes back even further than they thought."

In a storied career of more than 40 years, Sissy Spacek had never been a regular on a TV series. But she was already a Damages fan when she heard the Bloodline pitch from Glenn Kessler.

As the cast began to grow (locking up Kyle Chandler surely didn't hurt), Spacek decided she wanted in. "There's so much good work coming out of television," she says. "I wanted to be a part of it."

While she connected with hardworking matriarch Sally Rayburn, who runs the family's seaside inn, Spacek soon realized she was in for a whole new learning curve, especially in the TV world of KZK.

Gone was film's three-act structure. Gone was the luxury of brooding over a movie script for months. KZK has a different way of working. Their big plot points were mapped out, but the story was constantly in flux. The writer-producers were assessing on the fly, collaborating with the actors, following new leads and open to new ideas.

"We never really knew where it was going," Spacek says. But she didn't mind the mystery. "If you don't know what's going to happen and how it's going to end up, you're really in the moment."

Chandler, who'd never been to the Florida Keys before production began, was a master at staying in the moment as well — both on screen and off. When the cameras weren't rolling, he was often on his brother's 24-foot motorboat, diving and fishing with the cast and crew. "I forced myself," he half-jokes, "to insist to my wife on the phone quite often that, 'I'm working my ass off down here, honey, let me tell you.'"

Coming off five seasons as beloved Coach Taylor on Friday Night Lights, Chandler wanted some distance from that TV persona. He appeared as a supporting player in a trio of films — Zero Dark Thirty, Argo and The Wolf of Wall Street — that all earned Oscar nominations for best picture.

Now he's back as a series regular, but in a role that's a sharp turn from that high-school football coach. As John Rayburn — local cop, voice of reason, golden boy — Chandler is a decent man caught between right and wrong.

"They came down to Austin [where Friday Night Lights was shot] and pitched the idea," Chandler recalls. "I liked it. Then they came back a few weeks later, and I was in, because they were taking a chance on something. They had mentioned, 'We're not sure if this idea's going to work or how it's going to work. It's a bit of an experiment. But let's give it a shot.’ And that's when I was really in."

"There are associations with Kyle that were very interesting to us to be able to play off," says Glenn Kessler. "He has a certain kind of on-screen persona that we knew would be of great value. And we knew he could go to very different places than audiences may have seen of him in the recent past. He was interested in doing something very different."

Chandler also relished the chance to work with Shepard, whom he'd never met. "When I was a kid, my pop died," says Chandler, who was 14 when his dad passed away. "And there're a few scenes we do together [in which I] really get a sense of sitting with my pop again. So the scenes with him mean a lot to me."

For Cardellini — coming off her role as Sylvia Rosen, a neighbor and paramour of Don Draper on Mad Men — the opportunity to work with KZK was a big draw. “I was a huge fan of Damages,” she says. “So I understood how they make things.”

The actress was also drawn to the exploration of family and how, as adults, sometimes “you’re still in the roles that you were in when you were a child.”

Cardellini plays people-pleasing Meg, the youngest of the Rayburn adult children, who wants to believe the best about her troubled big brother. Like her character, Cardellini was also the youngest of four, with much older siblings. Her oldest sister married when Cardellini was three, so she basically grew up with three big brothers — just like Meg.

The actress therefore understands how siblings can experience their family life in very different ways. “The idea of the childhood that Kyle’s character and Ben’s character have is different than mine has, because in 10 years so much happened.”

And Ben Mendelsohn’s character — bad-news brother Danny — is looking to settle old scores. Many American viewers may be unfamiliar with Mendelsohn. But here, cast opposite recognizable faces from stage, cinema and TV, he is a scene-stealing standout. The entire series hinges on his ability to make Danny both scary and sensitive, a good-hearted screw-up with a streak of danger.

"He's the only actor we met with for the role," Todd A. Kessler says. "Not only does he have a sense of charm and playfulness and boyishness, but there's a sense of seriousness and menace — a weight to him. There's a substance to his presence."

Chandler loved working with the affable Aussie. "What a sweetheart. He's so easy to work with. And yet, he's tricky — when you're working with him, [psychologically] there's so much going on."

Glenn Kessler credits Netflix for not demanding a bigger name in the critical role. "They very much supported us finding the best actor that we thought could play the role. And that was Ben. He's an incredible mind as well as an incredible actor. He has a finely tuned sense of what's authentic — and what's authentic for the character. He was a real collaborator when it came to creating the drama."

Some viewers may recognize Mendelsohn from The Dark Knight Rises or The Place Beyond the Pines. In American films, he’s the feral outsider, but back home in Australia, he's a leading man, adept at slipping into many skins. So Mendelsohn was keen to tackle the challenge of a character some would call the villain. He doesn't share that view.

"The thing about Danny that appealed to me," he says from his adopted hometown of Los Angeles, "is that he looks very different, depending on where you stand. This world looks and feels very different depending on whose shoes you're standing in. To me, he's the hero of the family."

Another breakout character in Bloodline is the Florida Keys, which were a crucial part of KZK’s vision during pitch sessions.

"We pitched the show taking place in the Florida Keys," says Todd A. Kessler. "But once the deal was signed," he says, "Netflix asked us to do our due diligence" to find a more feasible locale. So KZK considered alternate locations in Georgia and North Carolina and along the West Coast, "but none of the water looks the same," Todd says. "And the whole culture of the Keys, it adds so much to be down there."

He cites a few reasons for shooting the entire series in the Keys, among them, the area's relative lack of production and its mythic stature. "Even if people haven't been there," Todd says, "they've at least heard of it. It can be a very strange place."

“The [biggest] challenge is the duality,” Cardellini says. “It’s perfect for the show. It’s gorgeous. It’s astounding. But at the same time, the heat during the summer is a lot to take. It’s incredibly beautiful — and a little bit dangerous.”

With production stretching over the better part of eight months — and only a two-lane highway leading in and out — the cast and crew couldn't help but become like family, succumbing to the rhythm of the Keys.

"There's just not as much stimulus as there is in New York or Los Angeles," Todd says. "So people spend a lot of their free time on the water. They're just looking to have a good time and enjoy their lives. There's not a lot of judgment. That definitely rubbed off on people."

Over the course of the shoot, there was a lot of hanging out and playing on the water. A pair of camera operators bought Chandler a spear gun for his birthday. The long stay also gave the cast and crew the chance to get to know the locals.

"If they had turned against us," Mendelsohn says, "we'd have been in real trouble. Big, big trouble."

Trouble wasn't a total stranger. Several months into shooting, cast and crew were dragging. Long hours fighting the heat and bugs were taking a toll, and morale was dipping. (Cardellini says she got 40 mosquito bites — the first week.) It probably didn't help that KZK's production style, so full of sharp turns and fresh ideas, had transformed the endeavor into a huge leap of faith.

"We were all in the same boat," Spacek recalls. "You know, when you're feeling a little lost and you look around and everybody is lookin' lost. You go, 'Okay, I guess that's how we're supposed to feel — a little lost.'"

"To be quite honest," Chandler says, "no one knew what the hell was going on. Once you're doing something for eight, nine episodes and you're down there for six, seven months — and you haven't seen a thing? Even the best of us can be like, 'C'mon, this is ridiculous.'"

So the producers gathered the dispirited cast and crew at a theater in nearby Homestead to watch the show's first two episodes. For Chandler, whose wife came to town for the screening, those two hours felt like 30 minutes.

"I was just so happy," he recalls. "And so was everybody else. Everyone had a bounce in their step after that."

Spacek came around as well. "I loved working on this," she says, "because it was completely new to me. It was like a completely different animal, and it kind of threw me off my equilibrium a little bit. And that's a good thing."

Cardellini was also delighted by the way KZK pulled it all together. “What’s incredible about the show is, you don’t believe your eyes,” she says. “You’re waiting for something to change, and for [what you’re seeing] to not be the reality. What you think is happening [goes through] twists and turns. You can’t really understand the show unless you watch it in its entirety.”

Chandler, who's got more dark turns in his bag of tricks, is itching for a return visit to the Keys. During a visit to New York City in March, he said: "I can't wait to find out officially that we're coming back, so I can pop open that magnum of champagne.”

Several weeks later, Netflix announced Bloodline had indeed been picked up for a second season. And somewhere Kyle Chandler was popping open that magnum — with more celebrating to come, no doubt, in the Florida Keys with his newest TV family.