LOS ANGELES (AP) ― There’s no summer break anymore for broadcast networks, with overachieving cable competitors regularly airing new series instead of succumbing to rerun laziness.

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.