'Under the Dome,' a high-profile drama, makes its debut during a packed summer TV season

'Under the Dome,' a CBS series based on Stephen King's novel, began airing this month. In previous years, 'Under the Dome' might have been saved for the fall, but TV programming for the summer months is getting increasingly competitive, say executives.

There's no summer break anymore for broadcast networks, with overachieving cable competitors regularly airing new series instead of succumbing to rerun laziness.

That's why NBC has "America's Got Talent," Fox is airing "So You Think You Can Dance" and ABC scheduled the flirty "Mistresses." Over at CBS, star students have teamed up for the ambitious "Under the Dome."

The 13-episode drama series debuting Monday is based on the best-selling Stephen King book and includes heavyweights Steven Spielberg, Neal Baer ("ER," ''Law & Order: Special Victims Unit"), Jack Bender ("Lost") and comic-book and TV scribe Brian K. Vaughan as executive producers.

Such firepower counts in this increasingly competitive season, said CBS Entertainment President Nina Tassler. It's even more crucial because CBS is rolling the dice with a drama, atypical first-run network fare in June.

"There is a lot of original content on-air during the summer, and there will be choices for viewers. Especially for us, for broadcast, we're looking for big-marquee auspices" such as those provided by King, Spielberg and their collaborators, Tassler said.

It's a smart move, said one industry analyst.

"It's about time networks put on these types of shows. Cable networks have been exploiting" broadcasting's seasonal weakness, said Brad Adgate of Horizon Media. "Putting on a high-profile series like this in summer is worth the gamble."

Tassler considers "Under the Dome" a safe bet, calling it the kind of escapist fare that "seemed to us to fit nicely as summer programming."

Escapist for viewers, just the opposite for the drama's characters. The premise is adapted from King's 1,000-plus-page book: The town of Chester's Mill (state unspecified) is abruptly enclosed by a mysterious, invisible dome. The residents can't leave and no one can come to their rescue.

How they carry on with daily life trapped in a social "pressure cooker" is the emotional heart of the story.

"Secrets bubble up because there's no place to hide. It's like Sartre's 'No Exit': Three people stuck together in a room, hell for eternity," Baer said, referring to the French writer's 1944 play.

For the people stuck in "Under the Dome," the questions are both existential and practical: "Why us? How are we going to live together, do we have the same government, how long will (the dome) be here, how do we sustain our lives?" he said.

While the premise is fantastical, the show strives to have a sense of realism for "our science-oriented friends and viewers," said Baer, himself a physician whose early entertainment credits include writing for NBC's "ER."

How permeable the dome is to elements including air, water and radio waves will be answered, he promised.

The summer slot allowed for a solid ensemble cast, Baer said. Hiring was done last winter, before other producers and studios had tied up actors for the flood of pilot episodes taped for the 2013-14 season.

Working with the casting directors of "The Walking Dead" and "Breaking Bad," Baer and his fellow producers picked actors including Dean Norris (federal drug agent Hank Schrader on "Breaking Bad") and Rachelle Lefevre ("A Gifted Man").

CBS executive Tassler said there was no arm-twisting to get Spielberg and the other big names to buy into the scheduling.

"At the end of the day, what do creators want? They want to be seen by as many people as possible. They want creative support and marketing support," she said.

Viewing levels (and typically ad rates) drop during the season's longer, warmer days as travel and outdoor activities draw people's attention away from TV sets and mobile devices. But producers who want to cultivate their network ties and opportunities recognize the value in helping expand broadcasting to year-round.

Helping make the business model work: The digital rights were sold to online retailer Amazon, with its Amazon Prime subscribers able to stream episodes four days after CBS airs them and after they stream on CBS.com.

There's no downside to a summer run, Baer said.

"We love it. We love going June 24 to September. There are no interruptions, no repeats. It's very predictable for viewers: You get a dose every week and then you're done," he said.

For now, maybe. While "Under the Dome" is considered a limited-run series in terms of its number of episodes — a baker's dozen compared with the 22 or so that air during the regular September-to-May season — that doesn't mean it's one summer and done.

The producers have "such a clear vision of where this show is going. We're prepared for success," Tassler said confidently. "Under the Dome" could return next summer and there might be a "winter cycle" as well, she said.

That has to send a shiver down the collective spine of imprisoned Chester's Mill.