The original “24” series starring Kiefer Sutherland officially turned 15 years old this month, and in honor of the milestone, TheWrap took a look back at the hit drama shot in real time.

Sandy Grushow, the former chairman of the Fox Television Entertainment Group, explained how he helped bring the show to air — and revealed how it almost didn’t happen.

From initial cost concerns to airing a show about terrorism after 9/11, what is now considered a modern classic nearly didn’t come to pass.

Read Grushow’s story below.

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A Strong Beginning

“It’s a great example of how fragile these things are and how many twists and turns they take along the way. They could go south a thousand different ways,” Grushow told TheWrap.

Grushow came across the script for “24” after it was recommended to him by Joel Surnow and Bob Cochran — pitched through Imagine Television to David Nevins and Gail Berman at Fox.

“Gail would send to me a pile of drama and comedy scripts that represented the shows that she thought were worthy of consideration for pilots,” he said.

“Within the pile of dramas was ’24’ — it was a tremendous script. You could tell just by reading it that it was really distinctive and groundbreaking. It was the first time I had ever seen a story told in real time. … with the dramatic ticking clock,” Grushow continued.

The show was potentially a huge financial risk. “The whole economic challenge came down to the hyper-serialized aspect of the series,” Grushow said, noting that serials tend not to repeat for networks and at that time were harder to syndicate. “Since we were going to be on the hook for both network license fee and studio deficit, the whole thing could have been a financial bloodbath, which is why there was any hesitation at all about ordering it.”

So Fox looked to the bottom line. “One of the things I insisted upon was we try to do it as inexpensively as possible, which meant producing the show in Canada to take advantage of the tax breaks on the order of about $300,000 per episode,” he said. “We talked about casting an unknown in the lead, thereby budgeting about $40,000 per episode for the Jack Bauer role.”

But as we all know, the role of Counter Terrorist Unit (CTU) Agent Jack Bauer ultimately went to “Lost Boys” and “Stand By Me” star Sutherland.

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Finding a Leading Man

“It was a bit of a struggle. Then late one night, I was in my office and I get a call. It was Tony Krantz from Imagine and he didn’t even say anything beyond two words: ‘Kiefer Sutherland.’ My reaction was initially mixed,” Grushow admitted. “Kiefer’s career had stalled … and I just knew that suddenly we were going to a lead that would cost, I assumed, $100,000 per episode, notwithstanding that he was pretty cold in the market at that point.

“Then Tony tells me there is a catch. Kiefer has a daughter who lives in Los Angeles, so we would have to shoot the show in L.A. Suddenly we were talking about a show that would cost about $350-400,000 more per episode.”

However, when asked for advice, Grushow’s boss Peter Chernin advised him to “use your best instincts.”

“So I slept on it and didn’t sleep well, but I came in the next day and thought, ‘Let’s go for it.’ And that’s how Kiefer was cast in the pilot.”

See video: Corey Hawkins Hunts Down a Mole in New '24: Legacy' Trailer

A Promising Pilot

“I saw a rough cut of the pilot … and it was extraordinary,” Grushow said. “It was amazing television. At that point, Peter saw it as well, because while I had greenlight authority for pilots, I would never order a series without Peter’s blessing. After he saw it, we both had significant concerns about the issues that were tripping me up in the pilot stage.

“It had huge advocates at both the network and the studio, understandably so, and Peter and I ultimately agreed it was too good not to take a chance on and we would somehow figure out the economics,” he said.

Fortunately, positive buzz came quickly.

“People in the press who saw the pilot early absolutely raved about it. We probably came out of pilot season and went into the fall season with the most talked-about new show coming to broadcast television,” Grushow told TheWrap. “We really spent a lot of money marketing it … and we were extremely optimistic about a huge premiere in November.”

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A National Tragedy

“And then of course the tragic events of 9/11 occurred. Suddenly, there we were … we had a show that was fundamentally about terrorism. So we had deep concerns about whether or not the American public would be remotely interested in watching something so taut and suspenseful about a terrorist attack. Needless to say we went into the premiere [which aired on Nov. 6, 2001] with concerns,”Grushow explained.

“The next morning I called the Fox ratings line like you had to in the old days and my concerns were proven correct. The show did not deliver the kind of ratings that I had expected. I remember literally pulling over and I was very disappointed. I called Preston Beckman, the head of scheduling, and I said, ‘Look, we need to run this show three more times this week.’ We had to get enough people to see the pilot to drive them into the second episode.”

Fortunately, the plan worked.

“Fast forward to January [2002]. We happily slammed “24” behind “American Idol’ [on Tuesday at 8 p.m.]. Even though it was shedding a ton of audience that “Idol” was feeding it, the lead in still protected the show and allowed it to really get its legs.”

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A Second Season That Almost Wasn’t

“We had a lot of conversations about whether we should turn it into an FBI franchise show, and there was a lot of spirited debate about that,” Grushow said. “But that fortunately ended with us deciding to roll the dice and hoping the audience would take the ride again. And not only did they embrace it, I believe the ratings went up by something like 25 percent, which we attributed to the DVD sales over the summer.”

In fact, Grushow said, “’24’ helped create the TV DVD market, which is one of the things that ultimately helped build the series’ ratings and financial success.”

The rest, as they say, is history.

Fox’s spin-off show “24: Legacy” will premiere on Feb. 5 following Super Bowl LI.