3rd Rock from the Sun - Season 6

Mary's sister comes back into her life and Dick comes up with a sneaky plan to help Mary get even with her. Meanwhile Sally and Harry open a youth center in the living room.

Dick and Alissa's father think that Tommy and Alissa have eloped. Can Harry and Sally scare up a date for Tommy?

Dick and Mary double date with Don and Sally leaving everyone feeling a little insecure. Meanwhile Mary and Don run into each other in a food store and, consumed by what they'd heard about each other in bed, share a kiss. Elsewhere, Harry and Tommy follow in the footsteps of Jack Kerouac and take to the open road.

Out of boredom, Dick, Sally and Harry go to a parallel universe and end up in New York where they all live the good life.

The Solomons begin to discover the downside of their new lives.

Tommy is looking for a college to attend and Dick steers him toward Pendelton. Upon taking one of Dick's classes, however, Tommy decides that Dick is a lousy teacher and that he would rather look elsewhere. Meanwhile, Sally is concerned that Don isn't listed one of Rutherford's ten most powerful men and so she gets him a job working for one of them.

Tommy goes off to college and Dick has to adjust to his absence. The Solomons start interviewing Tommy's replacement but Sally gets the hots for the new guy and makes him feel uncomfortable.

The Solomon family discover patriotism.

Dick accompanies Mary on an archaeological dig. Meanwhile, Sally, Harry and Tommy start up a bed and breakfast at home.

Mary has her purse snatched in a park, so Harry, Nina and Mary attend a self defense course that Don is teaching. Dick and Sally become a nightclub magician and a glamorous assistant.

After visiting a psychic, Dick decides to choose Mary's next mate so she won't be lonely when he leaves Earth. Meanwhile, Sally and Harry decide that if the psychic really knows that they are aliens, then they must kill her, but in a way that isn't possible for her to predict.

Sally's accurate predictions as the local weather forecaster have Dick fearing she will be exposed as an alien. Dr. Albright and Dick spend some time apart.

Dick tries to get to know Mary better, meanwhile Sally wants to go farther in the tv business and her mentor tries to give her some unexpected help. Harry gets a new job as a gopher and takes it literally.

Mary reveals to Dick that she has issues with her mother and Dick tells Mary's mother that she is a bad mother; Sally and Harry leave the portal open after using it and a alien life form gets caught in it and they have to take care of the new visitor.

Dick and Don go in halves on a timeshare; Harry has issues with his height when he finds out Tommy is taller than he is now.

Dick becomes obsessed with a book about happiness. Harry decides to paint the ceiling and Sally comes to Tommy's rescue when he is faced with hazing at college.

When the Solomons receive no recognition for their mission at the Alien Awards Show, Sally and Harry head out to try and discover who the winning team are. Dick is confused when he finds love letters that Mary has been keeping, which he didn't write. 

Dr Liam Neesam returns and declares himself to be Scoochie, the author of the love letters Mary has received. He reveals nefarious plans for Earth. Meanwhile Sally, Harry and Tommy discover there is a prequel to their favorite movie.

Having witnessed Dick's encounter with Liam Neesam, Mary is in shock. The Big Giant Head makes a decision about the Solomons' futures. Sally catches Don in a compromising position. Harry believes that he is dating twins.

The Solomons struggle with the news the mission is cancelled and they must return to their home planet. They hold a party to say farewell to all their friends on Earth. Elvis Costello entertains at the Solomon's going away party.