Mary's rich, spoiled sister Renata arrives in Rutherford. Dick formulates a plan to help Mary get the best of her once and for all. But Dick's falls in temptation when he gets a chance to live a life of luxury.

In an attempt to reconcile with Alissa, Tommy goes to her house with the feeble excuse that she still has the beer tap they rented for the senior party and he needs to return it. Strudwick snidely tells Tommy that he thought Alissa had given him his walking papers. But Alissa surprises her father by leaving the house with Tommy carrying a suitcase (containing the beer tap). A few hours later Strudwick goes to the Solomons' apartment looking for Alissa. Mrs. Dubcek observes that the evidence points to an elopement. Dick and Strudwick enlist Mary's help and drive off to stop the wedding.

Dick invites Sally and Don to join himself and Mary on a date. But when the conversation turns to their sex lives, Don and Mary have adverse reactions. Meanwhile, Dick and Harry take a road trip, but only get as far as the gas station.

Dick, Sally and Harry are bourd so they go to another dimension (through their shower) where they are all very rich famous and living in New York.

Things aren't going well in the Solomons' parallel universe and they want to go home.

Tommy can't decide where to go to college, and Dick is really pushing Pendleton: when it's all said and done, Princeton and Pendleton both serve fish sticks. Dick says he'll give Tommy a personal tour of the campus. Harry wants to go too but the other aliens remind him that he's not going to college. Meanwhile, Sally's upset that Don's not included in a newspaper article on Rutherford's ten most powerful men; she can't fathom how this is possible. Sally says maybe she's let Don down; maybe she hasn't thrust greatness upon him. It's time to rebuild him into the powerhouse he's never dreamed of being. On campus, Mary tries to help Dick recruit Tommy, but Tommy just wants to sit in on a class. Sally decides to throw a power brunch to turn Don into a success; she invites everyone on the top ten list plus other important townspeople. At the brunch, she wangles an assistant's job for Don with Gus DeMarmel, president of DeMarmel lunchmeat; never mind that Don has absolutely no business experi

The aliens give Tommy a big send-off to college, including two cases of beer and a fake ID, but as he's leaving Sally and Harry get ready to interview his replacement. The candidates have materialized in the closet and are ready and waiting. Both aliens are sold on Christie, an extremely efficient young woman, until they meet the incredibly handsome Bryce. Sally's bowled over by Bryce and hires him on the spot. Harry's upset, but he's quickly overruled. Meanwhile, Dick drops Tommy off at his dorm, and they reminisce about all the missions they've been on together. Sally's loving every minute that Bryce is around, but after Bryce's first day on the job, Dick decides to go get Tommy and bring him back. Tommy's already enjoying college and flirting with girls. Dick arrives and tries to convince Tommy to come home and go to Pendleton if he must go to college, but Tommy says he's not leaving. He does manage to convince Tommy that to impress the girls and really make a name for himself he ha

After attending a football game and observing how enthusiastically the crowd sang ""The Star Spangled Banner,"" Dick observes that humans have a deep love for their country of origin. They'd better get with the program or they'll look very suspicious. He assigns Tommy the study of the documents that created this country. Harry will cover anthems and epic poetry. Sally will do a microfiche search. Harry is put in charge of equality, since clearly it is one of the foundations of this country. Mary contributes that America offers so many freedoms: press, speech, assembly. Her family came over on the Mayflower. Nina says her family came over on a different boat but surely hooked up with Mary's family shortly after they arrived. As equality leader, Harry makes rulings on everything from who gets new shoes to the size of their ice cream sundaes. In class, Dick demands that the students stand up and say the Pledge of Allegiance. Sally is comfortable with the idea that all the aliens treating ea

When Mary invites Dick to accompany her on an archeological dig, he eagerly accepts; he's seen ""Raiders of the Lost Ark,"" so he knows how exciting and dangerous archeology can be. The Rutherford Garlic Festival is underway, and hotel rooms are at a premium. Since Dick's gone on the dig, the other aliens decide to rent out his bed. Soon the Solomons' apartment becomes ""The Inn at Solomon House"" with Tommy and Sally committed to giving their guests outstanding service in hopes of earning four stars in the Crown Travel Guide. Harry's not enthusiastic about the new venture, because he gets to do all the dirty work. At the dig, Dick's disenchanted when Mary gives him a trowel, a brush and an air bulb and tells him to carefully dust the sediment in one square foot of land. Dick grudgingly gets to work and later complains that he's been working five hours and all he's found is a pointy rock. Mary's astonished when she identifies his ""pointy rock"" as a spear head. She sadly confesses that s

While Dick and Sally form an act to entertain at children's parties, Mary and Harry get involved in Officer Don's self-defense class.

Dick and Mary visit Rita, a psychic, together, and Dick scoffs that the whole thing's a rip-off—until the psychic says that Dick and Mary are from two different worlds. She adds that one of these days Dick will leave Mary and go back where he came from. Dick immediately decides that he should devote himself to locating his successor, someone worthy who will wait in the wings until Dick has gone. Later, Sally tells Harry that if the psychic talked about Dick's leaving the planet, she must know they're aliens; they have to kill her. Dick takes Mary to a singles bar in search of the perfect replacement, but he acts so strangely that the bartender thinks Mary's a hooker and asks them to leave. Harry and Sally set about hatching wildly unrealistic plots designed to do away with the psychic. Nina tells Dick about Gary Hemmings, a visiting lecturer who's dying to substitute for him. Dick talks with Gary and offers him the chance to replace him; Gary thinks he's being offered a staff position

Dick gets a new camera and proceeds to make Mary angry by taking her picture against her wishes. Mary decides the two need a weekend off. Sally catches Harry walking around in the rain in her new suede jacket and decides that since the weather men can't accurately predict the rain they should pay for it. Upon going to the studio she then gets hired to be ""Sally Storm"" the new weather girl. Sally is told by Dick to stop being the weather girl after constantly being accurate, at which point they see that a major tornado will hit their area. Dick then remembers the college has a bomb shelter and proceeds to allow Sally and Harry to both bring one loved one to save from the carnage. Dick has to then try and get Mary to come, and does this by making Nina thing that an intervention(AA style) is in order.

After everyone convinces Dick that he doesn't know what Mary likes, he tries to buy concert tickets for the two of them.

When a new alien accidentally arrives through the time space portal, Dick tells Harry and Sally that it's their responsibility to take care of him. And Dick alienates Mary by taking sides with her detested mother as he tries to navigate through the minefield that separates the two women.

After Dick and Don each buy half of a timeshare ""luxury getaway,"" they take Mary and Sally on their first vacation there. Meanwhile, Harry's afraid of shrinking now that Tommy's taller than he is.

Dick thinks he's found the key to true happiness after reading Mary's favorite self-help book, so he rids himself of all conflict in his life -- including Mary, his main source of friction. Sally tries to help Tommy get into his college fraternity of choice by posing as the Assistant Pledge Master during Hell Week, but her grueling physical tests push Tommy to the limit. Meanwhile, Harry becomes tortured in his quest to re-paint the kitchen ceiling.

John Cleese reprises his role as Liam Neesam, Dick's malevolent alien nemesis in the first of a special two-part episode. In part one, Dick intercepts love letters sent to Mary by ""Scoochie,"" a secret admirer, and plots to interject himself into Mary's upcoming assignation at a Renaissance festival with the mystery man.

Dick can't stop Mary from dating her secret admirer ""Scoochie"" (really alien Liam Neesam), even though he suspects Liam is only using her as part of his plot against all mankind. Meanwhile, the rest of the gang find the ""prequel"" to their favorite movie, Arthur 2.

Mary is having some trouble dealing with what she saw: Dick transforming Scoochie into a monkey. Dick inevitably tells her the truth and she has a hard time to believe in it. Eventually she accepts it and even becomes fascinated by it. When everything seems to be going fine for Dick, Harry announces that their mission is over and they are to leave Earth.

As a result of the manner in which Dick settled his dispute with Liam, the group is ordered home. Of course, there are always loose ends to tie up before a long space trip. Dick wants Mary to accompany them, and Sally decides to instill confidence in Don. They organize a farewell party, and Harry and Tommy decide to charge everything and not worry about being around to pay the bill. They even hire Elvis Costello to sing ""Fly Me to the Moon.""