What a difference a year (not to mention a coffin, a crazed killer and hundreds of fire ants) has made for CSI.

Last season was a rocky one, both behind and in front of the camera, whether it was one of the stars reportedly being fired and rehired after a contract spat or the show’s investigative team suddenly splintering into two squads. Then along came the sizzling season finale, which reunited the teams in order to save a kidnapped Nick (George Eads), who faced certain death trapped in an insect-filled casket. But he survived, and his ordeal breathed new life into the series.

“We had a tough year last year. A real tough year,” reflects Gary Dourdan, who plays somber yet sexy CSI Warrick Brown. “We were just getting by, by the skin of our butts, to make it to the end of the year. The finale last season certainly gave us an uplift.”

That Quentin Tarantino-directed ending has turned into a fresh start for TV’s No.1 drama as it enters its sixth season, with the CSI detectives regrouping permanently into one team while struggling to cope with the emotional fallout from Nick’s near-death experience. “The ripple effects will continue,” says executive producer Carol Mendelsohn.

It starts with Grissom (William Petersen) uncovering a clue that proves the criminal mastermind who kidnapped Nick has a partner who’s still at large. “Just when you thought it was over, it’s just beginning,” Mendelsohn says. “What happened to Nick made them realize that life is short, sometimes shorter than they ever want to believe.”

Adds Eric Szmanda, who plays lab-guy-turned-CSI Greg Sanders: “Now we’re going to be more careful in how we approach everything. And we’ll be more conscious of bugs.” Particularly Nick, who doesn’t have to wait long before the writers find a way to bug him: There’s a scene early in the season where a big roach crawls on him, and he lets it creep up until it freaks him out.

Viewers - if not Nick’s coworkers - will be let in on his real state of mind. “What happened to Nick happened between him and the audience. The CSIs didn’t see as much,” Eads explains. “I want to keep [his reaction] between me and the audience. If I get the shakes, I’ll try to do it behind people’s backs. I can say, ‘I’ll wait in the car,’ and [the CSIs] will think, ‘What does he mean? Is he waiting in the car thinking about what happened?’”

While Nick’s trying to hide his reaction, Warrick stuns everyone with his very noticeable - and very personal - response to his buddy’s abduction. By the luck of the draw, Warrick escaped being the kidnap victim, and that realization leaves him so rattled that he makes a move sure to change his relationship with his sultry supervisor, Catherine Willows (Marg Helgenberger). “They’ll finally have that heart-to-heart a lot of fans have been waiting for,” Mendelsohn promises. “Catherine is thrown for a loop.”

Dourdan admits he “raised an eyebrow” after hearing about this top-secret twist but says he’s revved up about “the dramatic changes taking place.” Helgenberger though, seems a little less enthused because this could be the end of the characters’ flirty friendship that, she says, Catherine “hoped was going to be more than that.”

But Catherine isn’t just losing her potential love interest. Only a few months after being promoted, she’s also ditching her gig as swing-shift commander to rejoin Grissom’s gang. “She can relax a little bit now,” Helgenberger says. “She’s not having to watch her back as much. She will still carry the weight of a supervisor but not the responsibility.”

Will she and Grissom have a showdown about who is the boss? No one is talking. But Mendelsohn hints that Grissom’s wish to get “his guys back” at the end of last season’s finale will make him a different investigator now that his desire has been granted. “To some extent, this is a season about Grissom feeling [things],” she says. And his connection to his fellow CSIs “is a lot deeper than he’d ever imagined when we first began.”

Not only will there be an episode in which viewers finally learn more about the cranky CSI’s mysterious past, they may also get to see him open up in an unexpected way. A quadruple-murder case will take Grissom, Greg and Sara Sidle (Jorja Fox) out of Las Vegas. Holed up at a motel, Grissom finds Greg’s snoring to be too much and ends up right where fans have wanted to see him - sleeping with Sara. “They spend the night together,” says Mendelsohn, grinning. “What happens after that, we won’t say.”

This could be good news for Grissom but bad news for Greg. The youngest CSI’s crush on Sara will cool down considerably. They’ll continue to share a mutual discomfort around decomposing bodies. (“I did a scene with Eric that people are saying is the grossest thing we’ve ever done,” Fox says. “It’s a couple of bodies in the trunk of the car.”) But that’s going to be it. “He’ll always be smitten with her,” Szmanda says. “But he has to scope out other options. I like to think by the end of the season, he’ll have a love interest.”

That is, if he survives to the end of the season. A two-part episode is coming in November, and producers are planning a surprise ending that could make Nick’s desperate hours as bug bait seem like child’s play.

“It will directly affect the future for one of our characters,” promises Mendelsohn, who then pauses for dramatic effect. “Nobody is going to get buried. Only, perhaps, professionally.”