"Stupid, stupid, stupid!" Hugh Laurie chants over and over, his eyes closed. The actors around him try to give the star as much space as they can in this tightly-staged elevator scene. Is he throwing a tantrum? Engaging in a moment of self-castigation? Hardly - he's practicing. The line he's supposed to deliver to his team of underlings, Kutner (Kal Penn), Thirteen (Olivia Wilde), and Taub (Peter Jacobson), is this: "Tell her that the thing about emotional reactions is that they're irrational - or stupid." But for some reason, "stupid" isn't coming out American enough to the British star. "It just doesn't sound right," he says. The camera rolls, the director calls "Action!" Again, to the untrained ear, Laurie's "stupid" sounds about as Yankee as baseball. "Nope, one more time. Sorry." Surely, eight episodes into House's fifth season, the actor who's won two Golden Globes playing Dr. Caustic can relax about two tiny syllables? "The accent is the most frustrating thing for me," Laurie says later. "Almost everything else you do in life gets easier the more you do it. This one doesn't."

Laurie's struggle is hardly surprising when you consider that in season 5 - the point at which most megahit series are coasting - building Houses isn't getting easier for anybody. The thing about most growing pains is that they accrue over time - a sophomore slump, say, or an actor demanding a third-season salary hike. Not in this House. Last season, Fox's highest-rated scripted series (which returns Sept. 16 at 8pm) faced a confluence of obstacles. First, producers concocted a controversial story line - in which several key doctors left, and 40 fellowship candidates competed in a Survivor-like battle for a spot on House's team - that ticked off many loyal fans. Then came the three-month writers' strike, leaving producers with a truncated season and no real chance to adjust their creative course. "I think there were people who felt betrayed," acknowledges exec producer Katie Jacobs of fan reaction to last season's staff shake-ups. "But I think it's also fantastic that they would become so attached to our show that they would feel betrayed." Laurie, however, has a different reaction to the fans' discontent. "What would that be like if you said that to a person? If you said that to your partner, 'You know, I used to love you when you...'" he trails off. "I think your partner would think, 'Well, that kind of means you don't love me, then. It's not much consolation saying you used to love me when. If you don't love me now, you don't love me.'"

While the romance isn't over - the medical hit was still the No.2 drama on television last season, averaging over 17 million viewers weekly - House now finds itself in the bizarre position of launching its fifth season with something to prove. How are Jacobs and creator David Shore angling to reinvigorate TV's most compelling medical drama? By creating a stark series of befores and afters. Before, House and best friend Wilson (Robert Sean Leonard) had a fractious, codependent relationship. After - thanks to a fiery bus crash in the season finale that killed Wilson's girlfriend - the bromance is over. Before, costars (and fan favorites) Jennifer Morrison and Jesse Spencer were engaged in real life, while their characters dated casually on the show. After: The real-life relationship has fizzled, but the lovers will now take it to the next level on screen. Before, House and hospital administrator Lisa Cuddy (Lisa Edelstein) carried on a junior high school flirtation. This season, they'll finally be acting on the goose bumps. And in a move that may have spin-off implications, House stops using his staff to spy on the patients, and hires a private investigator who'll also spy on... the staff! "In series TV you've got to keep it fresh and interesting, while minding what's unique about the show," says Jacobs. "I really hope we've done it. I feel we have."

The trouble actually began with an ending. In the season 3 finale, House's original team of lackeys - Foreman (Omar Epps), Cameron (Morrison), and Chase (Spencer) - were all fired or quite, leaving the cranky boss to solve his own medical mysteries. "Everybody leaving House seemed like a natural result," says Shore. "He's not the type of guy you're going to work for in a contented relationship for five, six, seven years." The producers then hit upon the particularly House-ian way of finding a new team, in which House, to paraphrase Laurie, hires three doctors by firing 37 of them. While he toyed with a cattle call of candidates on a months-long audition spanning eight episodes, his original team was exiled to the farthest corners of the hospital. Foreman eventually found a role middle-managing the three new docs, but Cameron and Chase were relegated to a few lines per show - and were almost never together. "We were just trying to excite ourselves," explains Jacobs of the experiment, but "at the same time maybe we should have been smarter about the effects it would have." The effect was a message-board backslash, with many fans complaining that the telegenic duo had virtually disappeared.

Complicating the situation for Morrison and Spencer were rumors that their characters were sidelined to give the actors time to adjust after their real-life breakup in August 2007, a few weeks before House's season 4 premiere. "[Jesse and I] were still together when they made the decision" to hire a new team, refutes Morrison. The rumors might never have gained traction but for the writers' strike: Given the forced three-month break, several plotlines - including episodes that would have featured Cameron and Chase's budding onscreen romance - had to be dropped. "There was a whole stretch of story lines that had to shift and then got lost," says Morrison. "We went from thinking we were going to have eight more episodes to explore how Cameron's world was going, how Chase's world was going, how Foreman was feeling about [the new team]... All of a sudden, we needed a big finale."