Harry, Sally and Tommy return to Earth with Janet, a wife for Dick sent by the Big Giant Head to prevent Dick being distracted by Mary Albright
Dick tries to keep his wife Janet a secret from Mary, and Tommy admits to vandalising a field which Officer Don believes is the site of an alien landing
Dick and Mary play practical jokes on each other, Tommy joins a garage band to improve his chances with August, and Sally sets her sights on a yoga instructor
Dick accepts an invitation to spend the weekend with Mary's parents, who aren't aware that Dick and Mary have broken up. The other aliens help Nina move to a new apartment.
Dick runs away from the doctor's surgery as he's terrified of having a routine physical examination. On Halloween night, frightening noises in the flat scare Dick and Harry.
Dick puts on weight from comfort eating after falling out with Mary, but he struggles with his new diet and exercise regime. Tommy asks Harry to do some detective work.
Dick is called for jury service but finds the whole experience baffling. Sally is intrigued by a moody artist called Seth, making Officer Don jealous.
The aliens are irked by artist Seth's negative effect on Sally. Dick tries to adopt Officer Don as his new best friend, but grows clingy when Don has other social plans.
When Tommy studies the Seven Deadly Sins at school, it leads the Solomons to have a discussion around the dinner table about their adventures on Earth so far
When Tommy forms an attachment to Mary, Dick immediately becomes jealous. Dick thinks that Harry is watching too much television and orders him to stop for a week.
Dick bets Officer Don that he can rehabilitate a petty criminal more effectively than the justice system. Tommy suggests short cuts when Harry tries to write a book report.
Dick breaks his foot while playing around with a wheelchair and launches a campaign for more wheelchair ramps at the university. Mrs Dubcek's daughter Vicki visits.
Dick wants to start dating again but has no luck attracting women, so he places a personal ad in the newspaper. Harry and Tommy return a lost wallet to its owner.
Sally suspects something is badly amiss when hordes of beautiful women invade the town and start dating average guys like Dick, Harry, Tommy and Officer Don
Dick, Harry and Tommy's search for Sally leads them to the Venusians' lair where they discover the invaders' evil plan to enslave mankind through brainwashing
Fascinated by the concept of pregnancy, Sally pretends to be expecting a baby. Pickles, Harry's pet from the aliens' home planet, turns up on Earth in human form.
When the aliens shop for a new car, Sally falls in love with an expensive vehicle that is out of her price range. Dick has casual sex with a woman he meets at the cinema.
In an attempt to win Mary back, Dick surprises her at the library with a picnic. But his plan backfires when the two of them are locked into the building for the weekend.
Tommy grows tired of having to handle all the youth-related duties when he's the oldest member of the crew, so he decides to retire from the mission
Mary's father George comes to stay with her when his marriage hits a rough patch. Sally is charmed by his old-school manners and soon starts to fall for him.
Dick realises that his students are only studying physics because they have to, not because it inspires them. Mary gives Sally a job as her research assistant.
The Solomons think they are failing to blend into Earth society, so they try to be as average as possible, moving into a bland flat and abandoning all their quirks
Dick is frustrated when Professor Neesam proves to be his superior at sports, cooking, academic life and romancing Mary. Could this new rival be an alien too?
Sally is not excited by the idea of her first kiss with Officer Don and turns to romantic novels for inspiration. Harry and his class graduate from night school.
Dick decides that the aliens are not spending enough time together as a family, so he proposes a camping trip for just the four of them, but Mary wants to come along too
Dick's nose is put out of joint when Mary is asked to appear in a promotional video for the university. Harry takes Nina to the dentist to have her wisdom teeth removed.
The aliens are shocked to discover that Tommy has been hiding the fact that he's an accomplished chef, but his skills come in useful when Dick plans a dinner party