ORLEANS — From beneath her umbrella, Gracie Hosford has one eye on her 7-year-old son, Clancy, who is building a sand castle for the ages on the shores of Nauset Beach.
The 42-year-old mother of two from Phoenix, Md., has her other eye on the near distance, on the sparkling Atlantic, where seals dance delightfully and invite something more menacing: the great white sharks that like to eat them.
“It’s something we think about and we talk about,’’ Hosford said, squinting into a late-summer sun. “We talk about safety. But we’ve been coming here for seven years and that’s probably not going to change. It’s our family tradition.’’
On the beaches and in the barrooms, in the shops along Main Street and inside municipal offices along the outer Cape, this summer of the shark has seized attention and captured imagination like something out of a Steven Spielberg movie.
William Lytton of Scarsdale, N.Y., is recuperating after the 61-year-old was attacked by a shark while swimming in about 8 feet of water off Truro on Aug. 15, an assault that capped weeks of dramatic shark sightings and close calls.
The attack has people glued to shark-tracking computer apps, and has become the buzz along the beach. It also led to an extraordinary admonition from a local harbormaster who minced few words about what lies beneath.
“White sharks have bitten people along this coastline,’’ Nathan Sears, Orleans harbormaster and natural resources director, wrote on Facebook this week. “Fortunately, no one has died. . . . It is time for beachgoers to change their behavior or something terrible is going to happen.’’
Shiver me timbers.
It’s enough to traumatize any local official, like the mayor of Spielberg’s fictional Amity Island, who, in the film, deflected the local sheriff’s suggestion that the beaches be closed after a diabolical shark made a bloody feast out of a nocturnal swimmer.
“Are people nervous about it? Yes, more than likely,’’ said Noelle Pina, executive director of the Orleans Chamber of Commerce. “But with this risk has come publicity. The Cape is featured and Orleans is heavily featured on the Discovery Channel now, which we weren’t before.
“People are interested in things that are new. Great whites being off the coast of Cape Cod is new. So there are people who come and say they want to go on a seal tour. ‘Will I see a shark?’ They’re excited about it.’’
Excited. That’s one word for it. Here’s another: terrified. Or, to say the least, worried.
“I was saying to my friend the other day when he was sitting in the water with the seals, ‘Hey, that’s shark food. I would stay up here,’ ” 34-year-old Nick Johnson of Poughkeepsie, N.Y., told me as the Labor Day holiday weekend and the unofficial end of summer appeared on the national horizon.
“What are the chances that you do get attacked? So you don’t swim in the deep water and you don’t hold a metal pole out during a lightning storm. That’s how I look at it. I think it’s pretty secure. I believe that. I want to believe that.’’
So does Alex Ionescu, who was sitting beneath a flapping purple flag emblazoned with a white shark symbol by a beach entrance. Ionescu is 76, a native Romanian, and sells real estate in Manhattan.
He has looked into the eyes of the shark. And he knows that Spielberg’s mechanical shark in the 1975 blockbuster “Jaws’’ was simply the creation of Hollywood magic-makers.
“I was afraid to take a bath after that movie,’’ Ionescu told me. “Now, I’m not afraid because I saw the sharks. They’re just idiotic fish. I saw them in the water in the Caribbean in St. John where I used to dive among the sharks. They see you, they go away. They’re not interested.’’
Try telling that to William Lytton, who was placed into a two-day coma. The guy underwent six surgeries. He needed nearly 12 pints of blood to recover.
In just an eight-day stretch early in August, there had been 31 sightings of sharks in the waters off the Cape, according to the Atlantic White Shark Conservancy’s Sharktivity alert app, which has become a must iPhone accessory this summer.
But local merchants, whose livelihoods depend on the wallets of tourists, are quick to point to another data point. The International Shark Attack Files says only 26 people have been killed by sharks in US waters in the last 50 years. The last fatal attack in Massachusetts occurred in 1936, when a shark in Mattapoisett killed a 16-year-old.
“There have always been great whites down here, just not this close to the shore,’’ said Jay Mawn, who was celebrating his 50th birthday this week over a cold drink at the Land Ho! pub on Main Street.
“We all knew that it was just a matter of time,’’ said Mawn, who has been surfing here since he was 14 and grew up working on sport fishing boats. “I’ve seen them out there, going underneath us. You hope it doesn’t bite you and you swim to shore.’’
His childhood friend, Chris Dauphinee, said there is a fascination with sharks, a sort of dangerous beauty.
“It’s reality,’’ he said. “It’s a coastal town. You know what’s going to happen? A child is going to get attacked and that’s when things are going to shut down. It’s scary. I still go swimming. I’ll still go out for a dip. I have no problem floating around. Am I more aware than I used to be? Of course.’’
Dauphinee’s bloody premonition is enough to keep any local merchant staring at the ceiling at night.
Sid Snow is the president and chief executive of one of Orleans’ oldest businesses, a family department store that is the latest incarnation of an enterprise that stretches back generations. He’s 64, and as a holiday weekend approached, he was concerned about the economic impact of a beach shutdown like the one depicted in “Jaws.’’
“That was the closing of beaches for days,’’ Snow told me as we chatted on a bench at Snow’s Home & Garden. “That hurts. And the issue is being raised here now. The lifeguards generally close the beach for an hour. They make sure they don’t see the sharks. Then they open back up. In the movie, they closed the beach and kept it closed for a big holiday weekend.
“If all the beaches on the Cape were closed all day long the whole weekend, that would be tough. That’s going to give a bad vibe. How do we not scare people? How do we keep the beaches open? People have been coming to the Cape for years and they love swimming in the ocean. So there’s a balance. How much risk are you willing to take?’’
Back on Nauset Beach, Gracie Hosford was watching Clancy and his 8-year-old sister, Annabelle, on an afternoon where lifeguards briefly ordered everyone out of the water.
“Everybody back in Maryland is like: Why don’t you go to Bethany Beach or Ocean City?’’ she said. “But we love the adventure and the Cape. We think it’s really beautiful. We think you have something really special here.
“It’s a gem. We just love it. It kind of feels like — I wasn’t born then — but what the 1950s or 1960s would feel like. It’s not built up. There’s not a bunch of hotels here. It’s just people coming here to relax and soak in the sun, take in the food, take in the day, be with their family.’’
That’s an image any chamber of commerce would cherish.
Except for those sharks.
Thomas Farragher is a Globe columnist. He can be reached at firstname.lastname@example.org.