Last spring, during a presentation for advertisers on the set of the Monday-night hit "Las Vegas," series creator Gary Scott Thompson, NBC chief Jeff Zucker and star Jill Hennessey of the Sunday-night forensic drama "Crossing Jordan," bandied about the idea of crossing over the two NBC dramas, which air on adjacent nights on the schedule.

The result is a two-part storyline that begins on Sunday, Nov. 7 with the "Jordan" episode, "What Happens in Vegas Dies in Boston," and concludes the next night with the "Vegas" episode "Two of a Kind."

Although on the surface the gritty "Jordan" and the glitzy "Vegas" wouldn't seem to have a lot in common, Thompson thinks it's a good fit.

"On our half, it isn't a problem," he says. "We have jets, we fly whales [big gamblers] anywhere, so we can go anywhere and do anything. And for them to come here, everybody comes to Vegas."

On this Thursday afternoon on the Culver City sets of "Vegas," "Jordan" stars Hennessey, who plays Boston coroner Jordan Cavanaugh, and Jerry O'Connell, as Beantown Detective Woody Hoyt (Jerry O'Connell), are huddling with "Vegas" regulars Josh Duhamel, as security operative Danny McCoy, and James Lesure, as McCoy's right-hand man (and former parking valet) Mike Cannon, around the bar of the fictional Montecito Hotel.

Mike is attempting to summarize the first half of the plot, which focuses on a dead high roller with millions handcuffed to his wrist. By the time Mike tries to explain it to everyone, the widow is involved, people have been accused of murder, and there is something about a bunch of cookies -- "Chocolate chip cookies," Jordan interjects -- baked with poisoned cocaine.

As if this mouthful of a speech -- a bit over 16 lines in the script -- isn't enough (and, to his credit, Lesure nails it almost every take), apparently Lesure faces a worse one the next day.

"That's the one that really scares me," Lesure says. "The first one clicked for me quick, the one tomorrow is all over the place."

Asked why Duhamel didn't do more of the expository heavy lifting, Lesure laughs. "I don't know. I want the love scenes, and I want him to have the exposition. You can print that in the headlines."

In passing, Thompson hears Lesure's gripe about his lack of an on-screen love life, and shouts back, "You're gay. The show's never said he wasn't."

"This is true," Lesure says. "It's upsetting, if you're me. I got into this business partly to play with beautiful women as well."

While everybody thought the crossover was a good idea, on a practical level, it was another matter.

"When you do a crossover," says "Jordan" producer Tim Kring, "obviously, your actors are working on their show, and so they can't be working on your own show. What that means it becomes a logistical nightmare scheduling these things, so you can free up enough time that happens to coincide with the other show.

"Neither of our shows was shut down to do this, which would have been the smart thing. We had to fold them into our schedule."

On a personal level, the schedule worked out for new pals O'Connell and Duhamel, who got to visit each other's home base.

"I've know Josh for a while," O'Connell says. "I was excited to work with Josh. Was also a little excited to work with Miss Molly Sims, Miss Vanessa Marcil and Miss Nikki Cox."

"I love hanging out with Jerry," Duhamel says. "He's one of the funniest people I've ever met in my life. To go over there was even more fun. It's a morgue with dead people. We're over here with girls in tight dresses and lots of money.

"We've got two extremes: people who are living life to the fullest, and people who don't get to live anymore."

And, of course, "Las Vegas" has veteran actor James Caan, who plays "Big Ed" Deline, the Montecito's president of operations.

"Jimmy's great," O'Connell says. "Jimmy came over to our show. He's just classic. I learn a lot from watching him. He comes into a scene, and he knows there's one thing that's important in the scene, like one line or one moment, whether it's scripted or not scripted. He finds it and does it.

"If I could be half the actor he is, I'd be thrilled."

"Brilliant fun with Caan," Hennessey says after filming a scene in which Caan experimented with several approaches to figuring out how Ed should use Jordan as a shield to hide from his wife (Cheryl Ladd).

"We're using every opportunity," Hennessey continues, "to visually show some sort of sexual subtextural relationship. It's totally not written. He goes with it. It's so nice to work with somebody who's so good at improvising and so comfortable with it. I drop my eyes down to his pants, and he follows the lead. He goes with it."

While Thompson thinks a crossover with NBC's airport drama "LAX" might be fun, he dreams of linking up with an ABC drama about plane-crash survivors stranded on an island.

"'Lost,' that would be fun," Thompson says, grinning. "That could really be interesting. One of our planes crash-lands on the island [then is able to leave]. We say, 'Sorry, we'll send someone back for you.' Then we can't find it."