The sixth and final season of 3rd Rock from the Sun, an American television series, began October 24, 2000, and ended on May 22, 2001. It aired on NBC. The region 1 DVD was released on October 14, 2006.
Marys upset because her rich, beautiful sister Renata is donating a new wing for Pendletons museum. When Renata sets her sights on Dick, Mary is furious but Dick proposes a plan for Mary to get revenge. Meanwhile, Harry and Sally find out Renata is a philanthropist and convince her to give them ten thousand dollars for a teen center.
Tommy wants to get back together with Alissa, so he makes a date with her to watch a scary movie. Dr. Strudwick and Dick mistakenly think that Tommy and Alissa have eloped.
On a double date, Dick and Sally rave about how wonderful Mary and Don are in bed. Both Mary and Don are mortified. When Don and Mary bump into each other at a supermarket, they are suddenly attracted to each other. Tommy decides that with high school behind him, he needs to hit the road. Harry decides to tag along. They get as far as a broken down gas station just outside of Rutherford and realize they have no money.
The Solomons step into the time space portal in their bathroom shower and go to a parallel universe. They find themselves in a chic Manhattan loft. Dick is a high-powered attorney. He finds Mary working as a trashy torch singer. Sally is the author of a racy newspaper column about sex. She is dating Don, who is the mayor of New York City. Harry is the president of NBC, and Tommy is a hot-shot new cast member on Saturday Night Live.
Dick takes Mary who is going by the name Kiki to his spectacular loft and wines and dines her. Dick tries to persuade her that he loves he but she doesnt believe it. Sally is unhappy that Don is married and asks him to leave his wife. Don refuses, so Sally dumps him. Harry is forced to fire Tommy from Saturday Night Live.
Dick is trying to persuade Tommy to attend Pendleton, but Tommy isnt convinced. After sitting in on one of Dicks classes, Tommy tells Dick he is a bad teacher. Dick tells Tommy he is planning to quit teaching. Sally is concerned that Don is not included in a list of Rutherfords ten most powerful men.
Dick drops Tommy off at college, but the very next day begins to miss him. Dick tries to convince Tommy to come back, but Tommy is already enjoying college life. Dick helps him pull off an outrageous prank. Meanwhile, Sally and Harry have started interviewing for Tommys replacement.
After hearing a passionate rendition of The Star Spangled Banner, Dick observes that humans have a deep love for their country of origin. He decides the Solomons need to learn more about America. Tommy informs Dick that he is actually from Canada. Dick is worried that Mary wont love him if she finds out hes not American.
Dick accompanies Mary on an archeological dig, but is disappointed when all he finds is a pointy rock which turns out to be an ancient spearhead. Marys jealous because she has never found anything. Meanwhile, the Rutherford Garlic Festival is underway, and hotel rooms are at a premium. Sally, Harry and Tommy realize they can make extra money by renting Dicks room while hes gone.
Dick volunteers to be a magicians assistant at a childrens party and decides to become a magician himself. Sally decides to be his glamorous assistant. They wow the audiences night after night, but backstage they start to pick each others performances apart. When Marys purse is stolen in the park, she decides to sign up for a self-defense class that Don teaches at the Y. Harry also shows up at the class and gets the job of wearing the padded suit and being attacked.
Mary drags Dick to see a psychic named Rita. Rita predicts that Dick and Mary are from different planets and that Dick will go back to where he came from one day. Dick decides he needs to find a successor to take his place after hes gone. Meanwhile, Sally and Harry realize that the psychic knows they are aliens and must be killed.
Mary tells Dick she thinks they should spend some time apart. Dick is paranoid that its all over between them. Sally is upset with Harry for wearing her suede coat it in the rain. Harry claims he wore it because the weatherman said it was going to be sunny. After making a protest Sally is hired as the new weathergirl. Dick is concerned that Sally is too accurate in her predictions.
When Nina quizzes Dick about Marys likes and dislikes, its clear that Dick knows virtually nothing about Mary. Dick is determined to prove that he really does know Mary. Sally is a hit as the weather girl at Channel 10. Sally confides in the stations anchorman that she really wants to move into doing the news. Harry gets a job at the station as the stations gopher.
Dick tells Martha, Marys mother, that Mary really despises her. Martha gets so angry she falls down and ends up in the hospital with a broken hip. Dick promises to tend to Marthas every need while she recovers. Soon, Dick begins to see things Marys way. Meanwhile an alien appears out of the closet.
Dick hears a pitch for a timeshare condo and is immediately suckered in. When Dick, Sally, Don and Mary arrive at their vacation paradise, it turns out to be a dump. They realize that their only chance to get out is to try to convince their timeshare neighbors to buy a second one. Meanwhile, Harry is upset because Tommy has grown taller than him.
Dick, Nina and Mary are at a book signing for a self-help book titled A Road Map to Permanent Happiness. Dick thumbs through the book and is immediately converted. Dick realizes that the one thing that stands in the way of his permanent happiness is Mary. Tommy decides to pledge a fraternity.
Dick is poking around Marys dresser and discovers some love letters to Mary signed Scoochie. Mary mentions Scoochies letter suggesting they have a special rendezvous at the Medieval Festival. Dick finds out Scocchie is Liam Neesam, his old rival. Meanwhile, the Solomons are upset that once again they have won nothing at the annual Alien Awards Show.
Liam claims to be writing love letters to Mary for the last three years as Scoohie. Dick goes home and tells the aliens that Neesam is back. Dick decides he has to keep Liam from stealing Mary away. Dick is forced to turn Neesam into a monkey.
Dick is worried that Mary saw him turn Liam Neesam into a monkey. Mary questions Dick until finally breaks down and tells Mary he is an alien. Sally is upset when Don confides in her that hes too much of a coward to be a good cop. The episode ends with a shocking message from the Big Giant Head that the mission is over.
Dick wants Mary to leave Earth with him. After some persuasion she agrees to go. The aliens decide to throw a big party and say goodbye to Earth in style.