It is probably one of the more unusual phone calls that a meat processing plant has ever received.

When NBC decided to resume the reality show "Fear Factor," which last made contestants eat tarantulas and jump out of helicopters five years ago, the network said the stunts had to be much scarier this time. Dunking a head in 50 gallons of cow blood? "That’s nothing," said Matt Kunitz, an executive producer who, for the record, has never tried it. This time, there would be 3,000 gallons.

Enter the meat processor. "We said to the plant, months in advance, ‘Can you save all the blood from the cows?’ " Kunitz said.

The California plant declined to comment last week. But Kunitz said that last summer it dutifully stored the USDA-certified blood in 100-gallon drums for the television producers, allowing for one of the grossest stunts yet on "Fear Factor," which starts its second life on NBC on Monday night.

People in the industry are marveling at the return of "Fear Factor," the television version of a sideshow fire-eater or sword-swallower. But what is TV if not a traveling carnival?

"Fear Factor" originated on NBC in the summer of 2001 partly as a reaction to "Survivor" on CBS, which had become hugely popular the summer before. Although television critics detested the show, viewers seemed to love watching the contestants eat earthworms and pig livers and horse rectum. NBC has taken to calling it a "fan favorite" in its news releases.

"It was just a wild and crazy game show," said Joe Rogan, the host.

Almost immediately after the series was canceled in 2006 — a victim of overexposure and of a dreadful time slot opposite the No. 1 show on television, "American Idol" — the production company, Endemol, started to lobby NBC to bring it back.

"It was still very much in the zeitgeist," said David Goldberg, the chairman of Endemol North America, who recalled that when he took an old "Fear Factor" backpack on a family trip to Wyoming last year, many vacationers made comments to him. "People were saying: ‘Did you work on that show?’ ‘Why isn’t that show on the air?’ ‘I loved that show!’ I called up and relayed that conversation to Paul Telegdy," Goldberg said, referring to the NBC executive in charge of reality programming.

NBC, which has been mired in last place among the big four networks, warmed back up to "Fear Factor" in part because repeats were still running on Chiller, a small cable channel owned by NBC’s parent company, Comcast. By Chiller standards, the ratings were strong.

To bring the show out of retirement "it had to be bigger and badder and grosser," said Kunitz, an executive producer along with David Hurwitz. So in one of two episodes that will be shown Monday, instead of plucking rings out of the cow blood like last time, the pairs of contestants dive into a blood aquarium and retrieve cow hearts with their mouths. The pair with the most hearts will move closer to the show’s $50,000 prize.

"In the past we would have covered someone with 100,000 bees," Kunitz said. "Now we’ll cover one of them in 200,000 bees. Their partner, in order to get the bees off of them, has to eat 20 live bees, then retrieve an ax to cut his partner down."

Raising the perceived risks to the contestants gives NBC a new marketing hook; the network is promoting this season as "more explosive than ever."

The dangers may be more psychological than physical; Rogan said there was just a "little bit" of purging and vomiting by contestants. In 2005 there was a lawsuit brought by a viewer who said he vomited and injured himself after watching the show, but the suit was thrown out by a judge.

While the challenges have changed, the format — a physical challenge, a gross-out stunt, a grand finale — has not. Nor has the crew. "It was a really strange comeback," Rogan said. "The director is the same, the producer is the same, the cameramen are the same, the sound men are the same."

Some of the personnel now "have nicer cars," though, Kunitz said.

This time the crews worked with high-definition cameras, which may make the sequences seem more stomach-turning to viewers. For now Endemol has produced 10 hours for NBC, with the possibility of more episodes if viewers turn "Fear Factor" into a hit once again.

"It’s one of the more iconic brands in reality," Goldberg said. "So I think it deserves that shot."