Fourth-season opener: It's Roger's 1600th birthday, but the Smiths are too freaked out by Steve's impending puberty to celebrate. So Roger decides to make his own birthday fun.
Roger plays detective to track down a case of what he suspects is identity theft. Meanwhile, the Smith family gets sucked into a mean game of Simon Says.
Bullock makes Stan his “No. 1” at the CIA, a promotion that makes the furious Francine the “No. 1” babysitter for Bullock's baby son. Bullock needs someone to watch the kid because his wife's been kidnapped by Iraqi insurgents.
Stan learns that Francine was engaged to another man before she met him, and tracks the guy down to size him up. Then he wants Francine to choose between them. Meanwhile, Steve can't stay away from a schizophrenic cat that literally has nine lives.
Steve plots revenge after girlfriend Debbie (voice of Lizzy Caplan) loses a very dirty election for class president. But it backfires badly.
Hayley goes on a rampage after her boyfriend breaks up with her, but she calms down when she begins dating Stan's CIA body double, Bill. Stan heartily approves of the match, but the sight of Bill makes Francine queasy. As for Bill, he thinks Francine is hot. Meanwhile, Steve and Roger get jobs separating male and female chicks at a Chinatown hatchery, but Stan revolts when he learns what happens to the chicks after he's finished sexing them.
Stan emcees a CIA telethon to raise funds for the agency's torture budget after Congress slashed it. But Roger is out to sabotage it because Stan stole the idea for it from him. Lisa Edelstein has a voice cameo as a magician's assistant.
When Steve suffers indignities in school because of the back brace he must wear for his scoliosis, Stan confides in him that he wears a wig to cover his baldness. Meanwhile, Roger invites both Francine and Hayley to a posh spa even though he has only two passes, so he sneaks in Hayley in a suitcase, raising the suspicions of the house detective (voice of Forest Whitaker). Other guest voices include Jon Cryer and Niecy Nash.
Stan is ecstatic---and energetic---when a coworker (voice of David Koechner) gives him pills that allow him to stay up all night. He's also surprised when he discovers that instead of spending the time on hobbies, he'd rather spend it with Francine.
The Smiths catch Roger spending time with another family---and it turns out that he has been a family "cheater" for decades. Guest voices include Will Forte of "Saturday Night Live" as a security guard and comedian Ken Jeong as a psychologist.
When Langley Falls bans trans fats, Stan and Steve become smugglers. Meanwhile, Klaus gets word that he has received an inheritance but can't collect it because the CIA has turned him into a fish. So he has Roger impersonate him in his original incarnation (an East German). Guest voices include Forest Whitaker as Turlington.
Roger is mad at Stan, so he wrests control of the Langley Falls Homeowners Association from him, then abuses his power and changes the town's "American" character.
Steve connects with his ne'er-do-well paternal grandfather, whom Stan despises for many reasons, not the least of which is that he never taught him to ride a bike. (Others include his dad's criminal proclivities and, oh yes, abandoning the family.) Meanwhile, Hayley must find an internship for school credit quickly, so Roger hires her to tend his bar.
Steve and his friends sabotage a stuck-up kid's bar mitzvah after the kid (voice of Seth Green) hits on Steve's girlfriend, Debbie. But when Snot is wrongly accused of stealing the kid's bar-mitzvah money, his own bar mitzvah is put in jeopardy. Meanwhile, Stan and Francine pitch a cell-phone idea. Voice of Debbie: Lizzy Caplan.
Stan is kidnapped in Colombia, but the real trouble begins after he's released and returns home. Meanwhile, Steve and Roger play detective duo "Wheels and the Legman." Guest voices include Amy Sedaris (as Meg Penner and Carolyn Gilbert-Lawson) and Patrick Stewart (Bullock).
Steve and Stan, who don't have much in common, try to bond on a road trip to Albuquerque in search of a pair of the distinctive DeLorean doors to complete a car that Stan has been building. Meanwhile, Roger, Hayley and Francine decide to have an adventure of their own, but they can't decide what to do.
Steve joins a football team to please Stan, who then takes over as coach and gives Steve the boot because he isn't good enough. Meanwhile, Francine and Hayley vie for a blue ribbon at the county fair. Guest voices include Will Forte (Mayor Woodside) and Liz Torres (Councilwoman Santos).
Roger declares that he was sent to Earth to be "the decider" of humanity's fate, and Stan challenges him on it. Guest voices include Sandra Oh, Bob Odenkirk, Joss Stone, Grace Park of "Battlestar Galactica", Glenn Howerton of "It's Always Sunny in Philadelphia" and Geico caveman John Lehr.
Lois and Stan swap spouses with their gay neighbors Terry and Greg when Terry's dad, a former football player who doesn't know that his son is gay, arrives for a visit. Meanwhile, Steve goes on a drunken bender.
Season 4 concludes with Stan spending a night out with the guys and having a lot of explaining to do because of it. Meanwhile, Hayley and Roger charm a college frat boy. Guest voices include Joss Stone as an unattractive young woman and a hooker, Brian Doyle Murray as Al and Steve Landesberg as Bernie.