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 centre in the living room.

Dick and Alissa's father think that Tommy and Alissa have eloped.

Dick and Mary double date with Don and Sally leaving everyone feeling a little insecure.

The Solomon's experiment with leading a different life in a parallel dimension.

The Solomons find that people they know from Rutherford are a little bit too different in New York. 

Tommy considers college then calls Dick a bad teacher.

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.

Dick and Sally perform in a magic show.

Dick and Mary visit a fortune teller who tells Dick he will be leaving soon Dick tries to find Mary a replacement for himself to step in once he's gone.

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 favourite movie.

Having witnessed Dick's encounter with Liam Neesam, Mary is in shock. The Big Giant Head makes a decision about the Solomons' futures.

The Solomons struggle with the news the mission is cancelled and they must return to their home planet. They hold a party to farewell all their friends on Earth.