The day to day life's of three orphaned children who are adopted by aliens that have trouble adjusting to the local culture.
When Mel skips school she won't tell anyone where she's been, which gets her in loads of trouble with her teacher Mr Coleman. She eventually admits that she was visiting her mother's grave, but by then it's too late - Mr Coleman has already decided to pay a visit to the house, and could easily find out that Brian and Sophie are aliens. This is made worse by the fact that Brian has developed an unexplained allergic reaction to something which makes him sneeze uncontrollably and morph odd body parts all over his face! While this is going on, all Josh is worried about is having a party at the house to impress the cool kids at school. But just when it looks like the party will have to be cancelled for sure, it becomes an unexpected way of saving Brian and Sophie from detection - with a little help from some fancy dress...
When Lucy wins tickets to see Blink 182 in a competition, Josh is desperate to take them off her hands. After all, he's a huge fan of the band, and Lucy's such a geek she's never even heard of Blink 182. Lucy agrees to give the tickets to Josh, but on one condition - Josh has to perform a truly unselfish deed in order to qualify for tickets. Of course it's a terrible struggle for the scam-meister, but Josh learns a whole lot about himself in the process. Sophie and Brian start to think about Valux and discover the extraordinary phenomenon of homesickness. Only, being aliens, their sickness comes out in really surprising ways. And when Mel decides she wants to make Trent feel jealous, she chooses to go on a very unusual date...
When Josh twists his ankle in a Games lesson, Brian invents a Valuxian cure for Josh's sports injury. However, as with most of Brian's inventions, something goes wrong and the gadget makes Josh a chess and maths genius. Josh then has a choice to make about whether the benefits of genius are outweighed by the drawbacks of geekdom... But while Josh has become a genius, Lucy feels miffed at losing her identity as the smart one in the family. Meanwhile, Mel's life of fun and clubbing seems so sorted that Sophie decides she wants to go along too. When Mel points out that she won't fit in, Sophie decides to find a new look - much to Mel's horror.
At first, Brian is taken with the democratic ideals of the ancient Roman Senate, but when things stop going his way he turns into the equivalent of a Roman Emperor and imposes his will on the household.
It's Halloween, and Brian decides that he is a vampire. Who better for his first victim than Mr Whiteside?
After Trent says that girls can't be boxers, Harry signs up to compete in a tournament. Then, when her first opponent looks like a shoo-in at twice her size, Josh sees an opportunity to make some money.
After worrying that he will not be remebered when he dies, Brian goes on a guest to find the Holy Grail with CJ. Josh participates in work experience at the diner. Wendy and Lucy start a company producing potato powered clocks, and Sophie helps make them, however, she is told off by Lucy for giving them all away free. Sophie then founds Sophiecom International which sells useless coconut toys, yet these are a hit. Her buisness is about to go international until Lucy discovers her secret!
Brian doesn't notice CJ choking, so at Harry's suggestion decides to become a nurse, whereas Sophie becomes a photographer, Josh fights off a would-be girlfriend, and Lucy considers having her nose pierced so as to become "cool."
Josh and Brian vie to see which of them can tell the scariest Hallowe'en story, but Sophie can't understand why it's fun to be frightened.
Harry has been asking Sophie to do everything for her and Sophie is fed up with it. Lucy tells Harry that this is not a hotel and then Sophie gets an idea to make money and run a hotel though she hasen't thought a lot of it through.
Sophie helps Josh with a fake pet marketing scheme. Meanwhile, Brian has decided he can make a success of it in the fashion industry, but his style is totally wrong.
With Mell having gone to Canada, Brian and Sophie go to the children's home to find a replacement - Harry. Meanwhile, without knowing that she is his sister-to-be, Josh falls in love with Harry - a recipie for trouble!
After a visit from the ghost of his maths teacher's grandmother, Josh begins to mend his ways. But will he take Lucy's side over Santa, and risk not getting the mobile phone he wants for Christmas?
The aliens try to understand Christmas, but become confused about whether Santa really exists and who Lucy is playing in the school nativity play.
When the aliens discover that the children will eventually leave home, Brian makes his mind up to do everything possible to stop them.
Brian attempts to cheer Mel up with a string of comic disasters after taking his inspiration from classic TV comedy shows. But he does not count on the effect they have on her.
Brian acquires a new hobby - spoon collecting. And Sophie becomes a rapper.
Brian offers to get Josh a date with one of the school's fittest athletes, but things do not work out as planned.
Brian organises a break-in into the school in order to procure Lucy's school report.
Brian makes his first ever visit to the dentist - with hilarious results. And Sophie tries out a bit of body improvement.
The kids are outraged to discover that Sophie has but them up for sale on the internet - but what's worse is the price that she's put on each of them!
Brian discovers from a season of sci-fi movies on television that aliens are always shown as evil monsters. He sets about convincing the world that aliens are actually good guys.
Brian looks for meaning in his life and invents his own religion. Sophie is busy worshipping celebrities but soon turns into a celebrity herself.
Josh at last manages to get a date with the gorgeous Tania Thomas, but when he turns up accompanied by Sophie, disaster isn't too far off.
In the middle of the night, Brian performs an alien beauty make-over on Mel - but will it last?